88 Chevy 5.7L/TBI/700R4/Weird Problem

First: NO Check Engine Light. 150k original miles with the original engine/trans combo.

OK, as mentioned I have a 5.7L and I have a problem that is very hard to diagnose. Just today,I drove 2.5 miles without switching into overdrive ( 45mph zone), I jump on the freeway, get up to speed, shift into overdrive and then I cannot apply pressure to the gas pedal or I feel a lean misfire, hear popping through the TBI. I can actually feel it coming on as I get above 60 mph. But the kicker, Once I let off to go into coast mode and then go to reapply the throttle the problem is gone. That fast. Today, it happened just like mentioned above, I went 2 miles, got off the freeway and then grabbed a Coke. Jumped back into the truck, onto the freeway, did it once I shifted into overdrive going up a hill. Made it up the hill, crested said hill and then poof, gone. Not another problem remaining on the freeway for another 20 miles, stopping for about 45 minutes, getting back on the freeway for another 15 miles. This problem I DO NOT experience everyday. I can go months without it ever happening. I have only had it happen twice in one day, once. And it happened like mentioned above, drove over 50 miles and then happened in the middle of my drive going uphill. I use to be able to get it to do it going up a certain hill but, like I have said, once a month maybe. It has never happened twice in one week except for the twice in one day.

Parts already replaced. Ignition module, Coil, fuel pump and filter. Disconnected remote start for sh*ts and grins.
Parts installed aftermarket. Headers, Flow Master, Throttle body spacer.

I have over 20 years experience in the automotive repair industry and I am baffled at the moment. I am seriously leaning towards a PCM/PROM ?!?!?! Has anyone ever seen a oil sending unit for the fuel pump every cause an issue like this ??? I never have these symptoms below 60 MPH ( no tach, not sure of rpm’s). Lets hear from the Chevy gurus and see if someone could shed some light on this issue.


Answers for The Question

  1. Larry E
  2. adiabaticfire
  3. slipstream
  4. brad h
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