2002 s10 starts hard, runs hard

[divingduckman]

My 2002 s10 with the 4.3l vortex motor with msd ing, aem intake, air raid throttle body spacer, electric fan, ported and polished throttle body, full exhaust, and power programmer,and accell power truck tune up kit, just started to run hard ( hesitation ). Today i just had the code p0300 show up. It has ran fine. I thought it might be the programmer so i reinstalled the factory program that didn't help. it takes a while to get it to start (some back fires through the intake) the it runs like sh*t for a while then will run fine. The code p0300 is random/multiple misfires. Has any body had this happen to them???
the truck has 89000 miles
5 speed with hurst shift kit
zq8 suspension
Also it only does it after it has been sitting for a couple of days ( i work in the gulf of mexico offshore so the truck gets left at the dock).
please help