99redmustang

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). I have had an EVAP test done within the last year or so and no leak (I had the prior to the EVAP test). Do they check for VAC leaks during a EVAP Test??? Am I not checking something??? Could it be low on freon or something.

It only happens when I come to a stop!!! Any advice...Thank

liljojo4711

mine is doing the exact same thing... 99 gt

FrostByte

Make shure the A/C is fully charged & not cycling on & off when you are stopped.

meshow99

Was this problem ever fixed? If so, how. Mine does it. 00 GT Vert.

defconfire

Check your IAC your Spark plugs and your Fuel Filter.

sinister99GT

mind did it when the refrigerant was at low levels, recharge it and i bet it is fine,as long as there are no bad leaks.