Erratic Idle when stopped and AC is on... 1999 Mustang GT
I have a 1999 GT and I am having really bad idle surges when the AC is on and I come to a complete stop. The idle is fine when I have the AC on and the car is in in traffic...the idle surges from 300rmp to about 1400rmp and does this for the duration of time that I am stopped....sometimes it almost shuts off...
I've cleaned the MAF, clean the air filter (K&N), replaced the IAC valve, the EGR valve, PCV valve and I have a new ECM (about 3 months old). Am I not checking something??? Could it be low on freon or something.
It only happens when I come to a stop!!! Any advice...Thanks.
2011 5.0, Sterling Grey, Brembo Pkg and 3.73 Gears, GT/CS Valance, Roush Grille