Yes the problem started just after a downshift at high throttle going up a steep long hill pulling a trailer. I actually used a cheap bluetooth scan tool prior to taking to the first shop, but there were no DTC codes or pending codes.
Both shops supposedly used their expensive scan tools. The first one said the fuel trims are way off which indicates failing fuel injectors and once one has gone bad the others will fail soon, so I had to replace all of them. That didn't fix the issue so they were going to throw more parts at it and I argued paid and left. Even though they had not fixed anything, they said I had to pay them to take the truck. The problem symptoms had not changed at all, and it was evident they were just throwing in parts to get my money, no way was I sticking around.
I got some readings from my scanner, and posted those on the forum.
Since I could not come up with any ideas to change when researching on the internet, I took it to the second shop. The quickly decided the MAF was the issue and replaced it. When that didn't change the symptoms, they tried more troubleshooting. At some point they put the timing light on and discovered the distributor being off a tooth. They said the CMP Retard was maxed out at -24. Since the distributor had not been touched in 20k miles and they said it could not have been off a tooth without causing any issue, it must have changed recently somehow.
After the money I spent at the first shop, when the second was going to get it working for $750, I just let them spend hours and hours trying to get the timing right.
While the second shop charged for a MAF that did not need replacement, they did not charge me labor for removing the intake to get the distributor back in the right tooth, and spent like 6 hours trying to get the timing right. They did not charge me for all the labor working on the distributor. I figured I would have spent nearly the same for all the distributor labor as I did for that MAF replacement.
At this point, I don't know what really was the problem, but the issue is finally fixed. I just hope I don't breakdown hours from home again. I do not want to deal with mechanics.
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