85 chevy starts n idles fine runs good in 1st n 2nd but when it gets in third starts poppin m missin changed plugs wires distibutor cap rotor cap and distuntior its self. Also changed motor and same thing

SOURCE: starting hesitation, replaced plugs, wires,

timeing off or need a timeing chain

SOURCE: 95 GMC Jimmy 4.3l W vin rough idle

My problem was solved when I repaired my 4 wd activation dash switch. The switch was contacting on 2WD & 4HI at the same time. The front differential activation is vacuum activated possibly creating a tug of war that didn't actually engage it but drained off vacuum from the engine? A theory at best but stumbbled across it because I knew the switch wasn't working properly I repaired it and low and behold rough idle disappeared and all is good for 3 weeks running.

SOURCE: 85 vette starts but will not stay running

there is a sensor on the throttle body it' controls the idel of the vehicle it's called a tps and has a electrical lead to it this should be replaced it will be positioned right behind the butterflyplate of the throttle body

SOURCE: 88 chevy 350 knocking or pinging near front of engine

Just for the heck of it, have you tried upiing the gasoline one grade?

SOURCE: 1987 chevy S10 engine idle problem

relace the throtle air idle valve.The temp switch will allso cause this problem.