i dont remember the code number, but the description was "bank 1; insufficient catalyst". and suggested problems were: misfire, burning oil(or coolant), vacuum leak. i put in a denso o2, it definatly needed it, the original was very BAD. would a bad MAF throw its own code?

That sounds like a rear O2 sensor code, as that is the one that checks the operation of the cat. Our cars only have bank 1, and then sensor 1 - the one in the exhaust manifold, and then sensor 2, the one behind the cat. So, you may also be experiencing problems with your cat. Any noise or rattling from it? Does the car seem a lot worse once it warms up? The MAF may, or may not, throw a code if it is having problems. Some have had luck disconnecting the MAF to see if things improve. My experiences with that has been that the engine dies once it is disconnected, but it'* worth a shot.

no probs with the cat, its a new one from hogan(on a new 3"dp). thats one of the first things i changed because i thought it was my cat. i may change my back o2 also to see if thats bad too. where is that one plugged in? is the plug right there under that shield? or is it up further by the firewall? i think it specified sensor, but im not for sure.

ok, i disconnected my battery anyhow because it was suggested to reset my fuel "trims". never heard of it. but i took a test drive and it seems ok, didnt die any. we'll see if this damn code goes away.

How new is the fuel filter, could this be a cause?

thats also just been changed. man, ive replaced/upgraded alot of stuff chasing this gremlin. changed plugs twice(and wires 1st time), changed tranny fluid/filter, changed fuel filter, cat. converter, o2 sensor, LIM gaskets, etc. hopefully its fixed now, ill find out when i drive home today(35 mile drive).

died again on the way home. it was fine on the highway. it seems to idle at 500-600 rpm sometimes. i checked the fuel pressure, its at 46-48 psi at idle. is that normal? also, i noticed coolant on the LIM again! its either that stupid elbow leaking or something else is wrong. could my cylinder head(*) be cracked? im not smelling a bunch of coolant. the only thing i can think of is the only bolt i didnt tighten to torque specs is the one that holds the black bracket in front of the EGR canister. its not loose or anything, but could that cause a vacuum problem? i just checked the vacuum lines again, there all connected. also, when i was connecting the brake vacuum line to the "distribution block" on top of the supercharger, it popped off of the brake cannister and let air in. would that cause a problem?

also, i noticed on the way home that it idles at just under 1k until i "get on it" a little more, it starts idling lower. im thinking that i will replace the other o2 sensor to see if that fixes it. just now, it seems that when it was idling low, when i tried to give it gas, it got up to bout 1500 rpm, and stayed there, like it was retarding fuel or spark. :? im just thinking out loud. when i get paid, ill get the rear o2 and change it, since its about time to do that anyhow.

I don't think the rear o2 sensor is effecting the performance of your car. From what i know it simply makes sure the cat is doing its job. Even with a new cat and downpipe from hogan you'll probably see that code. I get a P0420 about twice a week once the car warms up and im about to delete the code once i get my tuner. I have a similar problem as yours and where im looking next is the ignition control module, check the resistance on your coil packs if you haven't yet, and then im going to start replacing ground cables. Alot of people have had this problem as of late it seems and no one has found a common problem yet. Alot of people seem to want to blame the trans and like you, i changed my fluid and based on what i found in the pan im not buying it. Good luck.

I'm watching this thread very closely. I seem to have the same issues with our 01 GS.

http://www.bonnevilleclub.com/forum/...ic.php?t=91893

I wish there was somewhat of a concrete "do this" type of fix. I just went through the entire engine less than 3,000 miles ago. All of my components are fresh. I guess the next steps would be the coils and ICM, but I hate to swap parts without really knowing what'* going on. Like throwing good money after bad out the window.....