A friend of a friend has a 98 24v that runs sporadically. When it does run, it runs great, he says. But at random times he can be driving down the road and the engine will greatly accelerate on its own, then has a huge power loss where the truck can't go beyond 25-35mph.
He says the truck has no tuner or programmer on it.

Any tips on what it might be?

Thank you for your time.

 

I'd scan for codes, then consider the crank position sensor, the vp, the ecm, APPS, bad batteries, steep terrain etc... it could be any number of things, the codes will greatly help narrow it down...