Got a 96 f150 5.8 runs fine when cold. But when it gets hot and I'm holding the gas cruising at speed and left off the gas the rpm gagues surge and sounds like it wants to die. All new plugs wires cap and rotor. No vacuum leak either what y'all think is the problem

 

Have you checked codes? Maybe something with the egr?

 

I bypass my egr like 6 months ago. I just put a new transmission in it like week and it never did this problem till now.

 

x2 on having codes read.

A couple possibilities (just a guess at this point):
*Trans is downshifting for some reason spiking the RPMs
*TPS is going bad or needs adjusted, verify .9-.97v closed and 5v WOT, with a smooth increase as it's opened and closed.

If your last post states that the trans was put in LAST week I would start with possible trans issues, a majority of the time new issues coming directly after preforming work on the vehicle are related to said work. Go back and double check any connectors that you disconnected, cleaning them up, verify proper voltage on sensors, etc...

 

TPS...clean Throttle body

 

Yes I put one in last week I meant to say. Thanks I'll get some tb cleaner and clean it and check tps out on it to.