I have a 1994 chevy pu 5.7. Starts and runs good, takes off good but when it warms up about 30 minutes or 20 or so miles it will not do over 50 and sometimes less.
I have changed fuel pump, throttle body, fuel regulator twice, fuel filter and new plugs and wires.
Still acts like is running out of gas at high speeds.


Any help woulp be appreciated.

 

Are you sure it's a fuel supply issue? or even an ignition issue?

Are you getting a check engine light or have you had it read for codes?
I'm thinking a transmission issue and your ECU is causing a Limp mode

 

Plugged catalytic converter? Pull the o2 sensor and try again, just remember that it'll be loud