I don't know if I did the post write 10 minutes ago I don't see it. My truck accelerates on its own sometimes like the pedal was pushed to the floor seem to happen after I put in a new alternator. I've went and put a junkyard alternator in and it's doing the same thing. After I shut it off a few times it stops doing it like nothing ever happened. Has anybody out there experiences problem with any good advice. Thank you in advance.

 

Welcome to the forum

What YEAR Ranger?
And what engine?

No, doesn't ring any bells

With engine off, open and close throttle manually see if its sticking, do the same with gas pedal, maybe cable needs so lube spray

There is an IAC(idle air control) Valve near the throttle, computer uses this to raise and lower idle RPMs, assuming 1986 or newer Ranger
It can raise RPMs up to about 2,000 if its sticking open