Diesel Bombers - runs and drives but barely

im new to this sight i have a decent working knowledge of most issues however i am trying to pinpoint what is causing this.. i have a 2005 6.0 with a 6 spd standard. egr delete is done both up pipes are brand new turbo is well within tolerance and doesnt appear to be leaking from the head at all i have not changed the ficm but im not sure if that would cause the problem i recently just changed oil cooler and did the hpop fitting because it cracked the rear motor plate on truck. when i crank the truck when its cold it takes for ever to start and spits and sputters for a while until warm after it reached full operating temperature never had a problem it always ran awesome and it would start without being plugged in eventually no matter how cold. now though its 90 degrees out if it sits more then 6 hours its a long start and and spits and sputters down the road and still misses after full operating temperature i got a injector contribution code on number 8 with my bully dog programmer and also a crank position code which im guessing is from cranking so long to start. it idles awesome it only spits and sputters under load. what are some rough ideas of what could be causing this i really am hoping its not the injectors but they all sound healthy at idle and on top of that you can here them when i hit the ignition im stumped and need a hand :argh: