1450-1500 rpm consistently fluctuations mimicking fuel starving then catching, over and over. With more throttle it smooths out. No codes present.

 

Vacuum leak?

 

Thanks, but double checked and all good 👍.

 

Our '02 does something similar when the VP44 relay gets flakey but it also falls on its face and has no power.

You're getting no other driveability issues?

 

It also cuts in and out under load at highway speeds like the fuel is cutting off and on.

 

Well typically the relay will set a "lost comm with VP44" code, but for giggles you could swap it with something like the horn relay and see if anything changes

 

Tried that, thanks, no changes.

 

Have you measured the pressure at the injection pump? You need at least 12+psi. How stock is your truck? Usually if the VP is on its way out it will start setting of codes in the ecm. You have any fuel leaking at the injectors? You done any recent repairs?