Tnbrock

I'm having some issues with my truck. We replaced the PMD(pump motor driver) a while ago. Not sure if it could be that again. We have put a computer on it and it is not throwing any codes. I'm having several problems, I'll try to explain them below. I want to say that everything it does IS COMPLETELY RANDOM. You never know when it's going to act up, we drove it several trips and had no problems whatsoever. First thing is that you can get in and start driving(the mph doesn't seem to matter) and the RPMs will shoot up to 4000 & 5000. Even letting off of the accelerator and taking it out of gear has no effect. You have to switch the truck off to get it to stop. Crank it up again and it runs fine for a while again. The other problem I'm having is that at, again random times, it acts as it is refusing to take fuel. I can press the accelerator and it jumps, jerks and doesn't want to go forward. As long as I'm in 2nd gear and let it go by itself and I don't press the accelerator it will do okay when it's doing this. We have also drove it somewhere, went in to shop, came out to leave, tried to crank the truck and it cranked then died out. After that, it wouldn't crank for a few times. Finally got it cranked(just kept trying it) and it drove fine for a ways. It's only done that maybe twice. The only other problem is that going down the road, if you take it out of gear to get ready to stop(usually only when in 4th or 5th gear) it won't idle down. In order to get it to idle down you have to either switch the truck off or put it back in gear, let off the clutch, drive for a sec. & try it again. (That doesn't always work and it's a pain when you are in town.) that's really all it's doing right now. Sorry that I can't be more specific, I am a woman and I don't know much about mechanics. Just want to figure out what's going on with my truck. Also, it has an aftermarket chip in it. Not sure if that could cause anything to go wrong. It's been in it for around 3 years and these problems just started about a year ago. Thanks for any help!