Hey guys, I have a 98 k1500 5.7 vortec. I was driving and the next thing I knew my truck lost power and would misfire at an idle but only when under a load (in drive with foot on brake). The last time something like this happened an injector came out of place. So that's where I started. I wound up changing the whole spider injectors and ALL the gaskets, upper and lower. I put everything back together and the problem was still there so basically I am back to square one. I then pulled spark plug wires while running to see if I could isolate the misfire and found that I could pull all 4 wires on the passenger side without any difference in while it was running. So basically my truck is currently running on 4 cylinders and they all happen to be on the driver side. I checked my compression on the passenger side and all 4 cylinders have 180 psi so that rules out the headf gasket being blown. I'm out of ideas at this point besides bringing it to a shop. I am getting 4 codes , 520, p1345, p0155 and p0161. I know that i have to get tge truck ptroperly timed with a computer but i dont think that would cause my problem. Any help would be appreciated.