Hello, I'm new here, so a little intro. I've got a stock, naturally aspirated 1992 SE Bonnie with about 198,000 on the clock. It has... well... a few problems.

It starts up great and runs just fine until the temperature gauge reaches just above 100 degrees. Once the engine is slightly above 100 degrees the idle starts to surge and often dies if I don't give it gas, it has no power in the lower RPMs, and pings/misfires/pre-detonates sometimes when I give it a lot of gas. If I can get it to above 3000 RPMs or so it typically takes off like a rocket.

It continues to run crappy until the temp gets up to about 200 degrees, then it usually runs fine again. On a few occasions it doesn't seem to have as much power and has to downshift in order to maintain interstate speeds.

I've replaced the fuel filter, air filter, O2 sensor, spark plugs, and wires within the last six months. I've also swapped in a junkyard throttle body assembly (with a cleaned MAF, throttle position sensor, etc.). Nothing has seemed to have helped.

The last fill-up I got 16.5 mpg, driving like my grandma about 50% city/50% interstate.

Any help you guys could give me would be great, as I'm at about my wits end. Thanks in advance!

It will help the guys a lot if you can check to see if you have any codes stored. Or have you already checked that? In this section of the Techinfo, there is a procedure for retrieving in one post and in another, a listing of definitions for your Bonnie:
http://www.bonnevilleclub.com/forum/...ode=cat&cat=12
Here is a picture of the connector. Pins A&B are for displaying codes. A bent paper clip works great. But if unfamiliar, be sure to read the procedure first.

The Sled'* Caregiver

Sorry, I haven't checked for codes yet. I haven't gotten a check engine light for I don't know long. I imagine the computer stores codes that don't throw CEL, just like most cars though.

I'll try to check for codes when I get off work, if it will stop snowing/sleeting for half an hour. I hate Iowa! I'll be sure to check them by Friday afternoon.

Thanks for the link by the way.

Knowing one way or the other on the codes is a good starting point. Did this come on suddenly or has been progressively getting worse? Do you have access to a fuel pressure gauge?

This thread shares some of the symptom but was coding (O2). Yours may be running lean like this one (By the way, Bosch O2s have a very bad reputation here.
http://www.bonnevilleclub.com/forum/...562&highlight=
Of course, you may have multiple issues. The above thread also shows where the computer'* ground is located. That is something to check, clean & tighten w/o spending a lot of time. You will also see a lot of discussion on looking for vacuum leaks. Either way, we will need more facts. I am only offering this side info in order to check some easy stuff while waiting for post replies from the REAL experts. BTW...I transplanted from Winterset, IA 34 years ago. Have yet to miss the winters. Now, AUG in Memph'o is another story.

In reading this I really don't get a good enough feel to offer advice yet, but one thing I know that I personally would check in your case, is the thermostat, along with the few other items mentioned by RedSled above.

Well, I ran my codes and the only thing that came up with was 58. Which happened to correspond to "Personal Automotive Security System ( PASS Key ) Fuel Enable Circuit," which means nothing to me. My ground looked like it was in pretty good condition, but I cleaned it up anyway.

It came on suddenly. I filled up with gas one day in the fall and it started to have all the problems I mentioned above, except it wouldn't run worth a crap, no matter what the temperature was. I had never really had any problems with it before. Well, I take that back, when I would drive it home on the interstate (60 miles or so) every 2 or 3 trips it would act like it didn't have any power for a while and the CEL would come on. If I took an off ramp and idle for 30 seconds or so it would run normally the rest of the way.

My replacement O2 sensor was a Bosch.
Should I look into getting a different one? If so, what company makes a good one? Thanks

Yes, get rid of the Bosch O2. Of course Delco is a good one, and I have heard others using the Denso. http://www.rockauto.com has a Delco unit. I paid about $48 plus not quite $11 for 2-day shipping. My 93 uses #AFS76.
http://www.gmpartsdirect.com/ has them even cheaper at about $31; same for shipping, but don't think it is 2-day. Didn't find that one until I had already ordered via Rockauto. Here'* a thread from the Lounge of how to get a 5% discount. http://www.bonnevilleclub.com/forum/...kauto+discount

Be hearing from you.

Well, I got a new code when I was driving the other day... "13--O2 Open Circuit" Looks like I need to order a new (good, not Bosch) one.