I have a 2004 ls 3.4 I get P0300 code starts fine idle is good at about 1800 rpm car starts to lunge bad up and down when its put in to gear at about 1500 rpm it starts missing bad can not find problem any help would be greatly appreciated.

thanks Jeff

 

Stuff to check:
When was the last time the plugs were changed?
When did you change the Trans fluid last?
Filters?
How many miles on this Car.

 

plugs plug wires changed 300 miles ago along with trans fluid have since changed mas and oxy bank 1 checked fuel pressure PSI 48 to 53
140000 miles