Hey guys new to the forum! I just wanna start by thanking everyone in advance for any input!

Im 17 an pretty mechanicly savy compared to other people my age. But recently 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. I replaced the heads with reconditioned heads because when i first bought the truck we thought it had a bad lifter but later learned the cylinder heads had a bad casting. I tore down the engine and replaced the cylinder heads 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. Now im down to cylinder 8 misfire. So i replaced the o2 sensors, and now im waiting for new catalytic converters(walker y-pipe) and then im goin to change the mass airflow sensor even though i did clean it, i did compress the cylinders with air and didnt hear any leaking from any bad/bent valves, i also put a new injector on the 8th cylinder and made sure it had one of the new coil packs. 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 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, please help!:/

 

did you do a compression check? Its possible you hydrolocked the engine and bent a con rod.

 

Yea did a compression check wich turned out fine, also squirted oil in the cylinder an no diffrence