yes, found code 34, map sig too low, replaced map sig now a litttle better, used propane tool to look for leaks found none, the i enrichend the mix but still cuts out @ 600 rpm.

i have a 87 gmc v1500 5.7 tbi. it has a stalling issue at 600 rpm . otherwise it runs great. the only time i can get it to idle at or below 600 rpm is when i unplug the timing bypass wire but it starts to surge a little +- 50-75 rpm. i scoped the tps and map and both are fine. seems to me that for some reason at 600 rpm a signal is dropping out. any ideas? any info would be greatly appreciated