Dano582

I have a 2010 Grand Cherokee, was told it was driven without water pump for 10 miles. Ran compression test no compression on number 3 cylinder all others between 125-130.Removed heads and found left side head had a valve seat that had fallen off and was holding valve open. Right side was fine, I replaced left head, lapped all valves both heads and replaced valve stem seals. The problem after reassembly truck started but had a 0300 code, multiple misfire. Checked and found right bank not firing exhaust manifold was cold while running. So far I have replaced all timing components and timed using Cloyes instructions. New plugs, wires, coil packs and injectors. Pulled engine apart to double check timing and found everything still in time, restarted with same results. Installed new crank position sensor and checked all 02 sensors and checked fuel pressure (60 LB while running) with no improvement. Right now truck will start and idle on 3 cylinders for about 3 minutes before backfiring and shutting off. Once it shuts off usually will not start until it sits for a few minutes. Hoping someone has a suggestion where to look next.