Need help withfor my 1996 Izusu Rodeo!

I just got my 1996 Isuzu Rodeo LS after more than a year. It had been in a repair shop that burnt down getting a replacement tranny. Took me along time to get it towed out of there cause of the fire damage. I bought another 96 Izusu for parts and had a mechanic take the tranny out of the one I bought to replace the one in my car. He also said he needed to replace trhe alternator belt. After I got the truck back it drove great on the way back home (like an hour trip) next day everything starts acting up loses power as if gas is not pumping at all, then all of a sudden it goes thru and acts fine. When I stop and put it in drive the car start revving up by itself! Doing 3000 RPM thought it would blow my engine. Also I think the belts are not right it starts squealing like crazy when I first start it and then it happens everyonce in awhile. I realize the car sat for along time and will need alot of things replaced but what could be causing the fuel problem and the squealing??

Any help greatly appreciated! I can't run it the way it is anymore.

New belts tightened properly ought to take care of the squealing...