still stumped 5.0 vortec start and stall instantlly

[baffledtonoend]

Hello, I am still working on my issue with my 1997 GMC sierra 5.0 vortec v-8, it now start's and stall's immediate upon first grrr, I open the throttle, same thing, so I decided to replace the fuel pump, it did same thing, so I pressure tested from shreadder valve and I get 61 psi at cranking and it hold 55 for 1/2 hour, So I replaced the filter, same issue, then I put in new injection spider triple checked all work so lines are in right cylinder's same issue start's and stall's in 3/10ths of second, so I went to ignition system, new plug's, wire's, d-cap, rotor, coil, and ignition control module, put in new ground strap' while I was at it, same thing but 2 code's from pcm p0102 and the p1351, so I thought to try taking out 2 plug's #2, and #4, pulled out of block and hooked plug wires up to watch for spark, yup it start's and run's with the plug's out and they have spark, put them back in and start's and stall's so I figured compression test, good in each cylinder, I am lostany help to get me going

 

[baffledtonoend]

still stumped runs on 6 cylinders not on 8 cylinders

Ok, I got the truck running like new so here's what I found, the original ownwer had brought the truck in to a shop and had brake's, exhaust, tune up and fuel system work done at a cost of 1100.00 and it would not run when they put it off the lift, so after putting in 800.00 worth of new part's myself and it still start and stall issue, I made a video and took it to all the local garage's in my area, dealership's too, so with all the head scratching and no answer's I thought about back tracking the work they did starting with the exhaust and guess what I found, they used a roll of gasket material to make a flange gasket off the y pipe to the intermittent pipe and sure enough the center of the gasket was not cut out so no exhaust gas could escape building back pressure choking out the engine, moral to the story, always back check others work ya never know what you will find, start and stall condition on most of these is a plugged cat, of exhaust gasket made by hill billy's lol