99 tahoe lots of high voltage codes

[Hunter Eiland]

so im new to this site but looking for help i have a 99 tahoe with 5.7 vortec
Back story 2 years ago i tried to install some headers but realized they wouldnt fit so i put the stock ones back on not to long after that i had bank one and bank two rear o2 sensor high voltage, did my research and made a new ground and fixed the problem few months later had a bank one and two front o2 high voltage so made a new ground then had maf high voltage took it to a shop they made a new ground and replaced a fuse then had map high voltage so I replaced the sensor and fixed that one : 1year ago new problem, took the truck around the block and it back fired three hard times then shut off and wouldnt crank ran the codes and came back with a cam shaft and crank shaft position sensor high voltage which would normally indicate that the timing chain snapped however my judgment is clouded from the rest of the other high voltage codes i havent had the computer tested but me and my buddy ( both of us millitary him aviation electronic tech me jet engine tech) opened up the computer to see if anything was burnt or fried and no results has any body heard of this issue or somthing like it? Any help is great help thanks

 

[PG01]

Sounds like you either crimped a wire somewhere, something is melting on the exhaust manifold, a connector isnt fully seated or the like. I would go over everything you touched