Has anyone ever heard of a distributor slipping? Not the timing chain...wondering if it’s possible for the dist shaft to slip on the oil pump shaft?

 

The oil pump is driven by the distributor and no it cannot slip. Remove the distributor and check the gear on it for damages. Is the truck going out of time?

 

I installed a new distributor about a year ago due to the original having the cracked/broken screw bosses that wouldn’t hold the cap tight. I replaced the timing chain shortly afterwards. Truck ran great for a bit. Recent issue is truck barely running, and small backfiring thru the intake and exhaust. Just checked timing last week—was at 0 on my scanner. Yesterday, it was at -44. I pulled #1 plug and cap to see if timing was off, and it appears the distributor is about 2-3 teeth off from #1 in ccw position.
ill pull dist today to check teeth. Thanks