Rkoa63

Hey guys I just recently bought my first mustang (90 GT with 73k original miles) and I replaced the cap rotor and plug wires last night(didnt change plugs because they only have about 300 miles on them). Now when the car is idling the rpm's fluctuate between 500-700. I checked all the plug wires and everythign is tight and in the right spot. I dont hear any hissing when the engine is running so I dont think its a vacuum leak( but i could be wrong). The car still runs and pulls nice when I'm driving but idling its a different story. Any ideas out there? THanks for any help in advance

Milky

Replace your 02 sensors. They should be replaced after 14 years and 70k miles if there still from the factory. Check leaks in your intake after the MAF

BlueStang225

try to pull the plug on the distributer? it is just hanging there in the front mine was doing that at track i pulled. with it i ran a 15.79 with out i ran a 15.04 and picked up 5mph. then i would try to clean your cold air intake stuff. i don't know what the little thing is called by the upper intake that is screwed on to side by the elbow, but we took it off and sprayed eather on in and it ideled better!

vfast

if it has a k/n filter I would clean your maf sensor

Rkoa63

THanks for the quick responses guys....Wouldnt I have had this problem before I changed the cap, rotor and plug wires? It was running fine before I did that stuff.

Milky

Ya, its likely not ignition, but stillc ould be... try doing what bluestang said but i don't think it would help. Clean your actual filter, or change paper filter, make sure there are no leaks on the intake

Rkoa63

No leaks in the intake...and the filter is about a month old.I also tried what bluestang recommended but still has the weird idle. This problem is really bugging me. But I do appreciate the help so far..

vfast

maybe try what I said..also is the cap on tight and check the pig tail plug in did you also replace the rotor button? did you use a cap with copper connections?...clean you t/b too..also what gap were the plugs?

Rkoa63

The cap is on tight and all the plug wires r good. The cap does have copper connections. And im not sure what the plugs r gapped at because the guy i bought it from had it tuned up before i bought it, but i talked to one of the local mustang shops and they recommended Autolite 24 gapped at .054 and then to bump the timing up to 14degrees. And also what is the correct way to clean the throttle body? I've been told that they are really touchy. I cleaned the IAC and the mass airflow meter with some carb cleaner and that helped a little bit. Thanks again.

BlueStang225

well make sure that the wires are not touchin the headers if they get on them that can cause it to idle fcked up