Nissan Repair: 1990 4x4 nissan 4cylinder, 4x4 nissan, power valve

Question
the truck starts running bad after it warms up . If you turn it off it won't start up until it cools down, then it runs good until its warm again. the distributor,and coil has been replaced

Answer
Scott,

If yours has a carburetor check the power valve.  It looks like a brass tube in the carburetor and it electronic so there are a couple of small wires that come out of it.  These are known to fail.  If yours is fuel injected check the EGR valve to make sure it is not sticking open after the vehicle gets to operating temperature.  But, my bet is the power valve sticking and is in need of replacement.