Start by taking you idle air control valve off of the throttle body . Check to see if it is clean where it bolts to the throttle body. If there is carbon inside the spray carburetor cleaner inside idle air control valve. Also use an old toothbrush to scrub where you've cleaned .Rinse the idle air control valve with carburetor cleaner and shake off excess . Try this first and that doesn't help then you may need to change idle air control valve.
1987 GT W/T Tops 5.0 With ported/93 COBRA Heads W/1.7 RR . Professional Products intake w/70mm T/B Lunati 501A1LUN cam 272/282 duration and 477 lift but 506 wit 1.7rr 1 5/8 Mac equal length shorty headers W/ 2.5 full exhaust and Flowmaster super 40's, BBK underdrive pullies ,Had 2.73,3.55,4.10 ,and current 3.73 gears with aluninum drive shaft.Just added 24lb injectors.
New just converted to Mass Air -what A Difference. Runs the best ever with NO idle issues.
Last edited by 87 T TOP GT302; 12-02-2013 at 12:50 PM.