rough idle in drive

[mississippiman]

i've been searching through these forums and have read alot about rough idle but have not found a post that matches my problem.

It all started on thursday night. We went out to eat and decided to take a ride through the country before returning home. We stopped and got some gas from a shady gas station that i normally would not buy gas at, however it was the only station for miles. The car was running fine, until about 10 miles down the road we stopped at an intersection. The car started to idle at about 500rpm, and the exhaust was louder, and it sort of vibrated. as we pulled away the car started running like crap. When you get up to about 55 the car sort of bucks or flutters. when we got home i checked the oil and it was a little low. So when you crank it it idles ok with a little vibration. when you put it in drive it idles around 500 rpm and is rough. if you slow down to stop it will die. and the exhaust sort of smells funny.

93 lumina EURO 3.1 130k

i think i might replace the IAC, but dont want to waste money replacing stuff that isn't broke. after all money is tight here in mississippi!

[maxwedge]

Sounds like a misfire? Try to isolate which cylinder is the problem. Check for spark on all the wires see if one is bad, then you may want to pull the plugs and look for one discolored compared to the others that may indicate the problem. These are the basic initial checks you should do here, your symptoms can have multiple causes. I don't what equipment or experience you have, so advice is limited to the simplest checks.

[rhandwor]

I would pull the fuel filter and check for dirt. Pour the gas into a jar like for pickles and after it sets for a while look for water on the bottom.
If you can blow through the filter it isn't plugged.
A bad plug wire will cause a rough idle. You can check these with an ohm meter.
You can clean up the idle air valve and reinstall it. Also check your air filter to see if it is dirty.

[richtazz]

Snce it happened right after getting gas at the "shady" station, put some dry gas and injector leaner in the tank and see ifit goes away. If it does, then you got bad gas. Report that station to the BBB or the Department of weights and measures, to prevent others from suffering the same fate.