I recently replaced the engine in my 99 K1500 sub with a gm performance HT383E. It starts up great in the morning but after running for a little while it takes a while to start back up. Also it is seriously lacking power. I had the guys from GM reset my timing to factory and that is when all of the problems started. Also I am getting a code saying that bank 1 is running lean. Need some Help! Any Ideas would be great!!