97 GMC sierra random misfire help

Hi i got my truck a while ago and it had a misfire so i got it checked and the #6 cylinder was dead. I put a new injector in myself and cleaned the rest with brake cleaner. Then it started with a random misfire so i put in a new cap, rotar, and wires. It just pops a little when its just about to shift but thats all. Does anyone know what this could be. I also have no catallatic converter or mufflers so this might have something to do with it but im not sure. Any help would be appreciated thanks.

Thanks

what motor do you have in your truck. if its the stock motor reguardless then you need a cat and some kind of muffler or your just gonna get floating lifters and sooner or later its gonna be bad.. your truck needs the backpressure a cat and muffler provide.. even if its free flow cats and a flowmaster..

I have the 5.7 vortec and im going to get a muffler soon.

Any check engine light? Codes pulled?

You said you replaced the cap, rotar, and wires, how about the plugs?

i wouldnt put it off much longer.. if thats your truck in your avatar then it looks like a nice truck and i would hate to see it hurt.. the vortec motors especially need the backpressure... they are so delicate that any bad sensor will cause them to go awnry on you.. i have a 4.3 vortec in my jimmy and have already been warned about what exhuast i put on it with the supercharger.. i have to get a borla system off made for your engine because of the muffler size and the amount of backpressure it needs to keep it in the safe power level

yah thats the one and i just put it away for the winter today. Im looking at a flowmaster super 44 right now.