97 tahoe runs rough

[wmike32]

First time posting wanted to see if someone could help out just changed motor because it was running like crap and misfiring now new motor is running the same as before tested ckps, tps, map swaped ecm still no change please helplong

 

[SunlitComet]

had you not read your spark plugs or tested them, cap, rotor and wires. getting access to the misfire history will tell you what cylinders are specifically giving you the issues.

 

[wmike32]

I changed plugs and wires before with old motor it made no change the only code I get is the dreaded p300 when I pulled plugs #2 & #8 were fouled out on old motor it also had bad compression on #2 that is why I changed it

 

[SunlitComet]

what about testing the rest of ignition parts or running fuel pressure test or injector balance tests.

 

[wmike32]

Changed cap rotor no change will do a fuel pressure check tomarrow and will get back with readings

 

[wmike32]

Fuel pressure was fine. Another cap rotor and removed cats. Bad cap, right bank cat failed. All codes gone truck running great. Only thing left is to get timing set by shop.