Rough Idle, no codes

Hello all. I have a 1989 PA with 183k miles on it. Recent replacements: air filter, o2 sensor, plugs (AC Delco) + wires, fuel filter, pcv valve, rubber vacuum hoses (all of what I could find), oil, and a new battery.

The problem just started today but I think my slowly declining fuel economy may have been a sign as well. I've only had the car for a couple of months and when I first got it, it was getting around 15mpg but after I replaced all of the above parts I would get about 22mpg. However, I've been getting around 16 the past couple of weeks. I've also noticed that whenever I let my engine idle, a large circle of black soot forms under my tailpipe. I'm not burngin up oil like mad and the spot is not a liquid...

Today, I was at Wally Wurld in the parking lot and I was maknig my merry way across the lot in idle (not pressing on gas) when my car started to chug like it wasn't getting enough gas to the engine (but has new fuel filter...). I hit the gas a bit and it resumed its normal purr. However, on my trip home it acted like it was going to stall when I began to accelerate up a hill and a yellow light on the left portion of my dash flickered on and then went off (too fast for me to tell what light).

It ran fine until I started uphill on the ramp off the highway. As I slowed down and began to turn on the road into town it acted like it was going to stall again, but no light this time.

I got the car home and checked for codes but all I got was good old code 12. I've got a couple ideas as to my issue:

-clogged EGR passageways
-Fuel Filter clogged up from old gas? (dont know how long it sat before I got car)
-Timing off
-ICM or coil packs going bad
-dying fuel pump

You guys lean towards any of them or have any ideas better than mine? I think I am going to try to get Autozone to get a fuel pressure test for me tomorrow (if they do that, i dont know...) to see if the issue is fuel related.

Thanks for any feedback in advance
-Eric

Running WAAYYYYY rich. I'd be checking the coolant temp sensor out. And your going to need to clean your O2 if the CTS is indeed bad.

Running rich would be caused by the coolant temp sensor? interesting...

Well, I ran into a couple of other interesting problems on the way to my university this morning. I was on the highway when my car lurched. It resumed normal operation other than my odometer, trip gauge, and speedometer quit untill I slowed down coming off the ramp after around 15 miles or so. The ses light was on during the time that my guages quit, but went off as soon as the guages came back on.

I'll try the paperclip trick after my classes (in the cafeteria at the moment) and see if the code was stored in the ECM.

Thanks for the suggestion!

The CTs is detremental to fuel trim then the O2.

Also the torque converter lock up function will be out of whack and could explain the "kurching"

Update for future reference: I ended up getting two codes later on. One was 63 for my EGR valve and a 31 for Park/Neutral switch grounding when in gear that I suppose got set off when my car almost stalled on the interstate.

Anyway, I pulled the EGR off of my 1990 olds 88, sprayed it w/ carb cleaner, and stuck it on my PA. I pulled the PA's O2 and sprayed the crap out of it w/ Carb Cleaner too. I've only run the car around town and so far no problems.

I'm going to buy the CTS if the problem pops up again, otherwise I'll leave the free fix as it is...it is convenient having a wrecked car laying around to borrow parts off of.

Another Update

I replaced the CTS after my car lurched again. However, the problem has not been solved. I'm still getting a code 63 (bad egr) although I have a totally different EGR valve on the engine.

At one point my car stalled and would not start again untill I gave it some gas while cranking on the starter.

Any more suggestions????