Intermittent hesitation/loss of power 86 2.9L

[jtmilazzo]

Any ideas what might be causing the following? 1986 2WD 2.9L. Starts and idles fine, except occasionally dies until it warms, then idles smooth. Starting off from stop, pulls fine, right up to 70MPH. Runs for 30 minutes, no problems, then (usually after going down a hill = high vacuum) when I get back on the gas, feels like engine has no gas, keep pushing on gas pedal, nothing happens, just "duuuuuuhhhhhh", then at about 1/2 throttle the auto trans will downship one gear, and "baaaahhhhhhhhhhh" the power comes back, it accelerates, upshifts, and everything is fine, until maybe 1 minute, maybe 10 minutes, it does it again. TPS has been changed THREE times, with no change, hot or cold doesn't seem to matter, but maybe more frequent when warm, no trouble codes (I have a good Actron Scanner). New fuel tank, in-tank pump and strainer. Runs fine on the interstate at 70+, until the problems occurs. ?????????????????
Your suggestions are welcome and appreciated.

 

[CraigK]

Sounds a lot like bad O2 sensor behavior. Try disconnecting the O2 sensor.

CraigK

 

[jtmilazzo]

Thanks Craig, I will give it a try.
jtmilazzo

 

[jvs8864]

hmmm
i have the same truck(86 RWD 2.9) except mine is a 5 speed
i noticed it every once in a while... didnt really pay attention to it
sorry i couldnt be more helpful lol