I have a 2000 Pontiac Grand Prix GT I picked up recently for $500, the car is in great shape with 110,000 miles on it. The car was running amazing till yesterday. As I was accelerating I could feel what felt like a hesitation or misfire, once you let off the gas the car cruzes great again no codes were coming up at this time. I plugged my computed in once the service engine soon light came on, the computer came back with a P0306 and P0306PD. If I am correct that's a CYL 6 misfire. What would be the main culprit of this? I was planning on starting with the easiest first, plug, wire then coil pack before I start doing anything with the injector or cats. I know with some of the other vehicles I have worked on that have a similar problem the coil pack was almost always the culprit. I have a large amount of mechanical knowledge and an auto shop worth of tools, however I have never owned a GM car before and know absolutely nothing about them besides that the 3.8L is a solid motor. From what I have read this problem is caused by everything from a bad spark plug to a clogged cat or bad fuel system on these cars. Also side note, the problem is getting more noticeable, the car still cruzes great at a consistent speed but is jerkey while accelerating, the same code is still appearing.
