Expert: Kevin Lawson - 11/26/2010

Question
I have a 93 chevy with a 350 tbi it will run great one minute then the next
I will start miss firing and fall on it's face. This has only happened after
sitting at idle few a few minutes but if you floor it then the truck will take
off like there is no problem. Would this be a fuel problem or what? The
truck has 198k miles on it and I'm not sure if anything in the fuel system
has ever been replaced. Any help would be appreciated, thanks!

Answer
It could be a fuel problem. Maybe a pump starting to act up or a pressure regulator that leaks. Has the fuel filter ever been replaced? The Throttle position sensor could be to blame and so could the idle air control valve. There are a lot of issues that could cause this. If you are mechanically inclined, you can get a chilton book for your vehicle and do the basic testing of most of these issues. If not, a shop would be recommended.