I have a 1997 GMC Yukon. We swapped the motor 5.7 Liter Vortec, with the same exact motor out of a 1999 Suburban.. Ever since it has been running horrible.. It has new plugs, wires, distributed cap and rotor, new fuel pump.
My car has 200000 miles.
My car has an automatic transmission.
The running rough may have something to do with the two different years of the engines but only a computer scan and fuel pressure test would be able tell. Have a certified mechanic, like one from YourMechanic, diagnose the car's rough running symptoms to see if the problem can be figured out. Good luck.
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