I have a 88 xtra cab 4x4 22re rebuilt less than 10000 miles. 5 speed when truck has been sitting a while it will crank up but don't want to run if you touch the gas for bout 20 to 30 seconds then runs ok. If you run the truck hard (60mph plus) or use the AC it starts to run hot I don't think its the fan clutch or the radiator & have changed fuel filter also seems to have no or little power at full throttle thanks up front for any help

 

Sounds like the fuel pump has issues. Not enough pressure to feed it right. There is a sock filter on the pump that may be plugged and restricting output. Sadly you have to drop the tank to get at it.

Could also be bad gas, drain it.

If you pull the tank out use one of those tank cleaner products.