eddiebray73

Almost a year ago i put the hood of my silverado 1500 4.8 under the water and ever since have been having problems. After scanning for codes i got a random multiple misfire (p0300). I replaced the heads with reconditioned heads because when i first bought the truck we later learned the cylinder heads had a bad casting and was burning coolant. I tore down the engine and replaced the cylinder heads and pushrods with no problem but after i started it up i still had the code, since then i have put 3 new coil packs, new wires, sparkplugs, o2 sensors, catalytic converters,mass airflow sensor, crankshaft sensor, intake manifold, i did compress the cylinders with air and didnt hear any leaking, i also put a new injector on the 8th cylinder and made sure it had one of the new coil packs because the cylinders misfiring i belive are 6&8 (havent scanned it in a while. I cant waiste any more money on this. Does anyone have any ideas? When i put it under the truck died an when i started it and it idled at 200rpm, an had to rev it up to keep it from dying an dropped it into gear. Now when it idles fine but kinda rough, and if i rev it to about 1100-1200 it dies but if i rev it any more or less the idles comes down fine, the check engine light flashes when i let off the gas on the highway, and the truck occaisionaly stalls when im going slow around a turn an hitting the brake, i dont think it has a vaccum leak because i used propane and used a vaccumm gauge, compression was within spec, and the fuel trim was good last time i checked, any ideas would be awsome at this point!