ignition timing decreases as TPS increases
 

Hi all, Great info on this site. Just picked up a 93 S-10 Blazer 4.3, for 3rd vehicle/ kids work car. Previous owner has a stack of recent receipts including fuel injector spider, ignition module, transmission. Vehicle would shut off and not restart for 30 minutes. Using your info, I determined it was the fuel injector connection. Next problem is lack of any power at wide open throttle. I use a Snap-on scanner, no codes, while driving vehicle and monitoring scanner data, vehicle runs strong as long as TPS is 30% or less usually less than 2 volts. When TPS increases above 30%, ignition timing drops to 10-15 BTDC. If I drive and monitor timing and keep timing at 30 BTDC vehicle runs strong. Will power brake, chirp tires at 1-2 shift. If I exceed 2V or approx 30% TPS timing falls to 10-15 and vehicle will not accelerate even when going down hill. I have been looking for info on this problem for several weeks and have not seen anyone else with this issue. I installed new AC plugs, wires, cap, rotor, coil. Looked inside upper intake for characteristic FP/spider problems, passed leak check. Any help would be appreciated, this vehicle is clean inside and out, just has performance issues. Thank you.

try replacing your knock sensor, if its not sending a signal your ecm will retard your timing , causing sluggish performance and would cause it to stall

I have same issue on My 93 4.3L Vortec engine
if you try to slightly push in on the accelerator which is normally controlled by The throttle position sensor. The vehicle Hesitates or stalls before accelerating.