have an 86 GT stock 5.0 with a 5 speed.

when i start the car it runs fine until warm,then it wants to die at take off or in low rpm range if throttle is mashed.when warm it surges bad at idle almost stalling out.its like the throttle is delayed about 1 sec from the pedal when warm.
sound like IAC,vacuum,or timing?will the IAC motor show problems after idle as well?im to my witts end with this problem

 

check your timing. also set your tps. its should be set at around .92 to .99.

could be you iac motor clean it out.

good luck.

 

fordguy,i did set the tps it is in spec and correct voltage with key on,cleaned the IAC,set timing.did notice no change in idle after unplugging the IAC.would that make a hesitation at anything other than idle.i get this stumble when i take off in 1 st gear and everytime i shift and get back into the gas.at idle it loped bad though,only when up to operating temp.

 

When was the last time you tuned your car up??(cap,rotor,WIRES,plugs). I had a bad problem like that and it wound up being bad wires. So try that first. Hope this helps.[sm=rolleyes.gif]

 

tuned it up bout 3 weeks ago....new plugs,wires,rotor button,cap,TFI module,MAP sensor,checked timing,cleaned IAC(still doesn't lower idle after you unplug it though),adjusted TPS,FPR,computer,harness,fuel filter,fuel pump,fuel lines,starter,and solenoid.

 

Well if you did all that and it still does it, then id start lookin for vacuum leaks. Oh and check your coolant level, on the older FI systems it would make the idle all eratic.

 

p zero,thats something i never knew(coolant level).i will check that out too though.thanks for the reply,this problem sucks !!!!

 

check 4 vacuum leaks

 

im gonna check again for vac leaks tomorrow,i posted earlier that i checked tha TPS.is it possible to get the correct readings and still be a bad sensor.i have it set at .098 now.the idle changes if i change the timing.gets better i mean but doesnt go away.it really hesitates when i shift in gears and give it gas or take off.drops the front end feels likef or a sec as if there is no power at all then kicks in where is supposed to be.if i cruise at a certain speed and give it gas it does the same thing,hesitates for a sec then kicks in.thanks for the replies.