idling issue
 

86 944 n/a 120k
recently aquired car. sitting 1.5 years. Got it started. Runs well "except" and there is always an except, the idle is all over the place. Sounds like the car wants to rev itself.
Starts around 1k then pops up to about 1.7k then back down and then up and so on. I might add this to the equation. Upon start the idle hangs at about 1k or so for a minute or so and "then" we have this up and down stuff.
Any suggestions: injectors, vac leak, sensors, etc and so forth.
newby

Timming or vacuum leak would be my guess.

o2 sensor possibly? Mine was old & gunky and caused rough idle.

sea foam, techron fuel additive, a tank or 2 of chevron sul.

Hunting idle.

2 possibilities.

TPS (throttle position sensor) - set incorrectly/ faulty
ISV (idle stabilizer valve) - gunked up/ faulty

anyway to test the tps and isv before I pluck bucks down.