Hi everyone, I'm new to the forum and I have spent about three hours using the search and still can't find a conclusive answer to my problem so here goes...

I've noticed my 92 bonneville SE runs hot, around 240 degrees, and if it is in park and I hold the throttle at around 3000 RPM, it will make popping sounds in the engine. Not a big problem but then it started surging going up hills. Now it will run okay sometimes then wont even pull itself over 10-15 MPH. Rich rotten egg smell when it does this. Also using A LOT of gas, around 1/4 tank in 10 miles. It also got worse when I replaced the fuel filter, it is installed in the right direction. I've replaced the ignition coil pack, it is all together, not 3 separate parts. Does that mean the coils and module are built together? Also the cruise works intermittantly. I'm replacing the plug wires today and the plugs were replaced 2 months ago the old ones all looked great and they had been in there for years. Thanks for the great topics and any help you guys can provide.
P.*. 188000 miles.

Also, I had it on the rack yesterday to check the cat converter and it tested out fine.

I'm thinking that alot of these problems are the from the over heating issue. You need to get your coolant system flushed, and while you're in there check your thermostat. From the sounds of it, it maybe stuck shut not allowing coolant to reach the radiator......240*??

Chances are you have a stock 195* thermostat. To test your thermostat, look at the thermostat, figure out what temp rating it is, chances are 195*. Get a thermometer that will register that high of a temp, and boil some water in a pot with the thermostat in there to check if it opens up all the way.

Best recommendation for a replacment would be a 180* thermostat.

Hope this helps, it'* atleast a start for the temp problems.

Also you should check to see if your electric cooling fans are working properly if at all. Easiest way to test the high speed fans is to turn on your A/C because the PCM commands them on at anytime irregardless of engine temps.

Thanks for the quick reply, I'm heading for the parts store now. The cooling fan is working, it was on when I was under the hood checking things out. I will get the cooler thermostat and flush the system. Wish me luck!

Good luck

Make sure you get the small rubber gasket that goes on the T stat along with the paper one for the housing.

Now that I think about it I used to have something kinda like that 10-15 MPH problem, but I don't think that my mileage suffered at that time, well because I stopped driving the car. But what fixed it was swapping back to my OEM coils.

garmar, were both cooling fans operating? There are two fans up there.

Both fans are working, I finished the work on it yesterday all except the thermostat. It is running much better now with the new plug wires. Also I pulled the fuel rail and replaced the injector O-rings and shot some carb cleaner at the ends of the injectors, (did not seem to be much else I could do, they don't seem to be servicable). I actually got some rubber at a green light yesterday, it has never done that. Now at WOT it bogs down and the RPM'* drop and I lose speed, but if I take it gradually up to speed it is fine. A year ago I was in Texas and when I was stopping at a light it surged like I was still on the gas, when I put it neutral (cause I thought I was going to hit the car in front of me ) it returned to idle. It did that twice and hasn't done it again. Could I have a malfunctioning TPS? Thanks guys for all the advice. Today I'm doing the 185 degree thermostat. I need a new radiator, I found a crack on the top of that plastic tank at the water inlet (thanks GM) so I'm going to park it for a few days until I can get one. Will the tranny lines leak alot when I loosen them at the radiator? I've never pulled the radiator on a car with an automatic. Thanks again guys.

Sounds like you are making big progress.

On the radiator change: The lines will not leak much when you replace them. As long as you drain off the coolant, you will leave very little on the ground for fluids. Most likely you won't notice much loss on the transmission dipstick when you check the level after the radiator change.

On the WOT restricted problem: How did you test your catalytic converter. Reason I am asking this is the excessive fuel problem you are mentioning is a typical sign of a bad O2 sensor. This sensor determines how much fuel in terms of lean or rich is being put into the motor. Usually O2'* fail on the rich side. Dumping tons of fuel into your motor and killing your catalytic converter. The catalytic converter will smell like rotten eggs. As well when it is in this killed state, parts of it have come loose and restricted the outlet to the muffler. This would explain some of the other problems you are having. When you are on the gas does it sound like you have a restriction? If replacing the catalytic converter is something you determine needs to be done. I'd suggest since it sounds like you are interested in power that you consider a high flow from ebay. Many members here have a Magnaflow and the price is much better than my local parts stores.

Good luck and keep us posted on how things are going.

Thanks for the quick reply Bill, I took the car to a very trusted muffler guy who put it on the rack, drilled a hole and put a sensor in the exhaust pipe in front of the cat. He also loosened the entire exhaust system and banged on it, he said he was listening for rattles. He said there wasn't a thing wrong with the cat. There was a very strong odor of rotten eggs when it was at its worse. I'm going to check the codes after I write this post and see if anything comes up on the O2 sensor.
Mostly I'm interested in the car not leaving my wife stranded on the way to work like it did the other day. But as soon as I buy her a new car, I get the Bonnie to play around with and I have a few evil ideas for it! That Magnaflow Cat sounds like a good place to start. Thanks Bill.

Well, I just ran the codes. All I got was the code 12 diagnostic. I hope this doesn't indicate something more serious wrong with the ECM. I'll keep working on it. Thanks guys.

If you know your Cat is good, I'd be looking more at fuel. Particularly the pump and the FPR. Can your mechanic or you get a fuel pressure gauge and check it?

Looks like your exhaust guy knows his business well, and you're getting great guidance here, too.