Calling all old schoolers.......

Maybe a fuel line collapsing and cutting the fuel. Or someone shoved a wash cloth down in the gas tank?

 

sounds like a fuel pump, maybe the last one put in is junk, put a pressure gauge on it and watch it when it happens

 

could be a myriad of things from:

1) cracked fuel line TO the throttle body

2) cracked return line TO the fuel tank

3) pick up tube is cracked or not deep enough into the tank

4) could be dirty/varnished throttle body butterfly

5) could be dirty/varnished MAF sensor

6) could be a bad MAP sensor

7) could be bad coolant and not reaching proper temp for sensors to work

8) could be a bad battery/not holding voltage

9) could be a bad/poor ground, at the fuel tank

10) could be back pressure in the CAT converter or muffler

11) could be soft "rubber" fuel line collapsing

12) could be a bad or low-flow fuel filter

you will ALWAYS get different readings at idle and under a load (like when actually driving)

 

A lot of motorhome chassis of that era have a inline fuel filter that is in a spin on mount about the size of a soup can.

Crawl underneath at the fuel tank and follow the fuel line forward to see if this is the case, if so unscrew the housing, clean the housing, replace the filter, fill with gas, remount.

 

when was the last time the transmission fluid was changed?

 

My '87 Ford had a similar issue. Changing the fuel filter and cleaning the contacts on the high pressure fuel pump fixed it. My truck has low pressure pumps in the tanks and one high pressure pump on the rail. Can't remember exactly where they switched to high pressure pumps in the tanks but I think it was around '94

What sounds different about your situation is that you can pull off, restart, and it works fine. Engine temp drops too? That sounds like a ground problem