A little bit about the car its a 86 iroc z, it has a 350 block out of a 83 c-10 with a tune port injection system of a 91 camaro. I bought the car in september and drove it for about a month. And then i started having problems. My car wants to die out if i dont pump the gas pedal when im at a stop. But it will start right back up. So i tested the fuel system and it is putting out the right amount of psi at the injectors. Then one day i was trying to start it and it would run as long as i had my foot to the floor, as soon i would let off it would backfire and die. And when it was running there was a strong smell of fuel, leading me to believe it wasnt firing right. I tried advancing and retarding the timing, which did absolutely nothing. The cap, rotor, plugs and wires are all brand new. So i thought it might be the timing chain, which it wasnt. The only other guess i have is right before i bought the car the previous owner changed the valve stem seals, and whwn he tightened the rocker arms down he got them to tight. Any ideas on what it could be?