misfires only going down hill on deceleration on 2000 Chevrolet Silverado 2500

have a 2000 chevy 2500HD silverado 6.0 gas motor. I have an issue where when i start to go down hill and coast a little bit and let off of the throttle down to about 1/10th throttle the truck down shifts out of overdrive, sometimes i get a p0300 misfire with the engine light flashing. the wierd thing is this only happpens when im going down hill on deceleration. it will kick out of overdrive, sometimes the check engine light comes on sometimes it doesnt. but once at the bottom of the hill the tranny will not shift back into overdrive for atleast a mile or two. this is on the highway around 70 miles per hour. if i stay on the throttle or if im under load it doesnt do it but if i am on the throttle pedal just a little bit and i start to coast then it kicks out of overdrive. if i let off the throttle all together and coast say from 75 to 70 then back on the throttle it wont do it. so i have to speed up and let off all together to prevent this from happening. this is really anoying. i have a air intake, msd coils, hypertech programmer, eldebrock headers.. new plugs, new wires, new throttle position sensor, new fuel pressure regulator, new fuel filter.. I have heard people say crankshaft postion variation relearn procedure could fix this because of slack in the timing chain, i guess that would kinda make sense because that would be about the point that the tension would shift from pull to push or load and no load. please help, thanks

by in Canton, OH on March 12, 2013
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1 answer
ANSWER by , March 12, 2013