Ok here's the deal...I have an 85 GT that I just put a fresh 306 into...it started and run great so I took it for a drive and as I was out driving I stepped down on the gas one time and it "stuttered"...then ran like crap, backfiring through the exhaust, and VERY hard starting...acts like its way out of time...the engine has the E303 cam, Edelbrock 600 cfm carb, Edelbrock RPM Performer intake, 1" Carb spacer, shorty headers, o/r H pipe, Magnaflo mufflers, and it also has a EBay distributor with the ignition control module mounted on the side of the distributor...I've set TDC a hundred times checking the piston physically to make sure its at TDC and both valves are closed...all the timing marks match up great...I can get it to start and run but I have to manually turn the distributor for it to start then turn it back to have it idle...the position of the distributor when it will idle will not work to start the car...the vacuum advance seems to be working cuz if I take it off it runs very rough if at all...any ideas or suggestions are welcome...I am very frustrated with this...I've been working at this for almost a month now...thanks for any and all info.