throwing code p0306?
new wires plugs rotor cap o2sensors and mass airflow sensor on 1997 GMC Yukon

this model has throttle body
and distributor

high missfire when accelerating

2 answers
What did the plug cyl. #6 look like when you took it out ? was it oil fouled? was it indicating a 'lean' misfire? Compression & valves/rockers good? Vacuum leak from intake?
possible coil