Massey850 it seems you are correct. I was quoting what I read researching your problem, the stalling after warmup. One reason for that is a crank sensor going bad. OK so RA does not have a crank sensor for the 88 dak. Haynes manuals may help, I think I have one, but the Bishko Factory service manual has everything. It's about $40 for a CD version from them, the original publisher. It is probably worth it since the 88's have several differences from the later gen 1's. That said you may still have a compression/stuck rings problem. If you aren't into trying that oil flush just adding a quart Risolone might help. It is supposed to loosen up things.

Edit- It also occurs to me that if changing a couple sensors made such a difference you should replace any of them that look old. That
s 34 years old When I did the plenum on mine after I got it I replaced all the sensors in the intake and on the Throttle body.

 

Isn't the 88 throttle body injection? I didn't think the crank sensor came about until the debut of the magnum engines, in 92?

 

Ok so I've made a discovery. Twice I've gotten the truck to start when it does its problem with a bit of ether down the throttle body so that would mean that it doesn't have enough fuel to restart. So now I'm suspecting the fuel delivery system. I don't think its the pump mainly because its a heat problem.

 

Something is failing under heat soak conditions. These can be a real paint to track down. What the issue is, is a solder joint or similar component has a very small crack. As the part expands, that crack expands with the rest of the part. Eventually, it opens the circuit. The fun part is finding where the failed joint is. I would start with a coolant sensor. I've had issues with those in several different vehicles over the years. Different brands included. You can try putting a bag full of ice on different components to troubleshoot this. I had a failed brain box on a Diplomat once. It ran fine cold but hot it would stall. A new box cured the problem. I took the old box apart and wiped Prussian Blue high spot indication on the wires.With a really large magnifying glass, I found a cracked solder connection inside. I could have soldered the join and reused the box, except I wasn't gentle getting it apart.

 

OMG! That's worse than looking for a cracked head.

 

Test the fuel pressure when it is doing this to see if there is fuel under pressure at that point.That way you know it isn't the pump for sure and the problem is down stream of that. IDK how you'd test fuel pressure on an 88. The later models have a schraeder valve on the fuel rail.

 

Yes and no. A sandwich bag with crushed or smashed ice set on different components can usually track this down.It just takes time and attention to detail.