Missing back fire

[Holt50]

Try a fuel pressure check. Key on eng off, running idle, running hiway.(long hose on guage under wiper on windshield) Also time on leakdown. Fuel pressure spec 60-66#.
Another place to look is fuel trims with scanner. Check steady state hiway. Report findings.

Did fuel pressure test idle running but not driving need to find a longer hose also checked every spark plug with plug tester and all is well there man this is frustrating oh and fuel pressure stayed at52 for awhile before going down 52 at idle and 61 when wide open

 

[Eman85]

370,000mi, stop throwing parts at it. First basic test is a compression test then go from there. Put a vacum gauge on it and see what the reading is, is it steady? Have you had it scanned for codes?

 

[strutaeng]

You either need to invest in a scanner that has live data and watch a few hours on basic diagnostics on YT on how to interpret the data, then look into what has been suggested in previous posts,

OR, just bite the bullet and take it to a real mechanic and let him figure it out.

Unfortunately, the parts changer approach sometimes doesn't work because you may wind up replacing otherwise good parts with (sometimes) inferior parts from the parts store. Now you are out of ideas, out of patience, out of money, you have introduced more unknowns (even new parts are bad out of the box!), and you still have a vehicle that's broken.

 

[exp500]

Did fuel pressure test idle running but not driving need to find a longer hose also checked every spark plug with plug tester and all is well there man this is frustrating oh and fuel pressure stayed at52 for awhile before going down 52 at idle and 61 when wide open

Fuel pressure is a definite suspect, range is 60-66. My experiences are some may miss at 60# slightly.
Put a cheap scanner on it and monitor fuel trims to decide whats next. Fuel pump, relay, oil pressure switch are usual suspects here. Show key on eng off/ at idle /at speed and leak down time 5#.
The Service manual has very good troubleshooting charts.
Look here- https://www.tahoeyukonforum.com/threads/helpful-links.131971/