1999 5.0l wierd acceleration issue

Have a 99 5.0L mountaineer and had the vehicle accelerate for no know reason. thye rpms would go up either in drive or reverse ane the brakes would not hold it back and the truck would shot in either direction. I talk to a mechanic friend of mine he sugested the idle control valve which i replaces and the issue went away for a month and a half. But now it seems to do it again out of random. Can anybody help wih this issue. Thanks

Welcome to the forum!

Have you checked the throttle plate operation to make sure it operates smoothly and freely? Have you checked that the floor mat isn't somehow interfereing with the accelerator pedal operation? How about the throttle cable, is it routed properly and not hanging up?

How high are the rpms getting? It seems odd that the brakes won't hold it unless you have a serious vacuum leak that is causing the power brake assist to not provide assist. When the engine speed increases, is it constant or is it cyclic? What do you have to do to get the rpms back down?

-Rod

like a said its a random. no kinks in cable to lean in throttle body and no vaccum leaks that could be found. no rug in the way. no check engine light. it did it once this weekend and twice today. like i said at random times.