What do you people think of this

[82_mustang50]

Ok, i changed motors in my mustang from an 82 to an 83 HO. when i had my old motor in it i didnt have any problems with peeling out or anything. but when i put in this new motor i had no power. well i thought maybe the timing was off. so i took off the vaccum advance and plugged the hole. well all of the sudden my rpm's went way up so i messed with the idle speed. made sure that the timing was still where it was supposed to be and i reconnected the vaccum advance. well now it has the power that it should have. should i be worried or not. the guy at autozone said that i shouldnt mess with it. the motor had been sitting for around three or four months maybe more. then the car was sitting around for a few more after that. maybe something got knocked loose? should i be worried about the sudden surge in rpm's? it seems to be running fine now, temps fine, oil's a little low, idle kinda surges but i havent really messed with the carb yet so i hope thatll change if thats all my problems i can live with a little surge? so should i do anything or leave it be? no pinging or anything. thanks for your patience in reading this any comments will be appriciated.