1990 Chevy Beretta 6 cyl Front Wheel Drive Manual 260000 miles
My car when I'm at driving speeds acts fine when I slow down or driving slow it has a low idle, I've changed the plugs, wires, pcv, egr valve, idle control valve. Don't have any clue on what it could be.
I have worked for gm for a long time and this engine 2.8w or 3.1t engines are very tricky to get to idle perfectly. The gm scan tool called a tech1 has a program in it to reset the idle air control valve. First of all you have to start with a clean throttle bore and tps voltage at close to.68 volts with a throttle angle of 0. If you have access to a scan tool you can check the tps voltage and set it as close as you can and if it shows a throttle angle at all, you can reset it to zero by disconnecting battery once you have the correct tps adjustment. They only used this system for a few years then they changed designs.