94 502 efi's. One motor seems to have trouble running when shifting. Followed the instructions for setting timing, tps and iac. Base is set to 8 btdc, tps is .47v, and I can't get iac over 20 (trying to get to 40). Could this be a sign of leaking plenum/manifold or something else? Any help is greatly appreciated. Thanks

No codes either

If the idle is set at 900 let say and its idling HIGHER than that and the iac counts are at zero or close to it either you have a vacuum leak or the throttle blades are set open too far and the iac has no control. If the idle is below the target and the iac counts are low then you have other problems, Smitty

try .58 to .60 volts for tps

Requested rpm is 800 which it rides right at, iac has some control with secondary screw all the way out. The max I can get is 20-25. When tps voltage was higher it didn't go any higher. When I shift you can see on the comp and hear the airflow change but it seems like its not enough or fast enough. Also since I changed timing back to stock it idles ok but randomly dies. Mech pump rebuilt as well as vst has new seals and recently cleaned. Both iacs are new as well.

Any ideas?