my idle is acting up again too. :jerkoff:
pain in the ass problem to have, seems too common.
solutions range from bad grounds to bad motor mounts.
my grounds & mounts seem solid but i could be wrong, cap rotor plugs wires all new.
im starting to wonder about other possible causes, kind of ripping my hair out.
mine seems more like a low speed miss than it is a rough idle, but it comes and goes and its only happens @ low idle speed & engine warm.
hoping its not a cylinder compression issue, but 2 other things listed were - map sensor and throttle position sensor
i dont know if that would have anything to do with your problem but its a few more relitively easy things to test out.
compression, map sensor, tps sensor
another idea may be to take a decent length of vacuum hose and use it as a sort of stethascope, with the engine idling stick one end up to your ear and run the other over all your vac lines, intake & throttle body gaskets, FITV & IACV gaskets, injectors, brake booster line etc etc.
if you have a vac leak what will help you find it, listen for the hiss.
pull off the brake booster check valve and suck/blow into it make sure it doesnt leak any air in the closed position.
i plan on replacing all the vac lines tomarow or something, i figure… why not, cheap & easy to do.
here is some other stuff.
No leaks around the intake manifold? The next most likely suspect is the power brake booster. Pull the hose off with the engine idling and plug it with your finger. If the miss goes away, the diaphragm in the booster is leaking or the vacuum hose connection to the booster is faulty.
The air conditioning system is the next most likely culprit. Remove the line that provides the A/C vacuum from the intake manifold and plug the port with your finger. If the miss goes away, use the 3/16" tubing trick to listen under the dash board to locate the source of the leak.
Still no luck? Check the remaining vacuum lines that connect to the intake manifold. Pinch each line with needle nosed pliers. The engine will smooth out when you’ve pinched the right one. If the hose has several branches, pinch close to the intake manifold first, then work your way down the branches to locate the one that’s leaking. If pinching cracks the rubber hose, it has reached the end of its service life and should be replaced anyway.
(Note. Pinching the PCV hose will cause a change in engine rhythm even if the PCV system is working properly.)