We did a frame off restoration on a 93 Ranger. It was a 3.0 manual 4wd, we got a wrecked donor truck that had a reman 4.0 engine and manual transmission, also 4wd with about a 1000 miles on engine and transmission. We pulled cabs off both truck and installed engine and transmission as one assembly.
When stepping on gas and letting off or under hard acceleration AFTER switching gears the truck jerks like when someone does not know how to drive a stick shift would jerk it. There is also a banging noise when it jerks.
During the restoration process, the place we had sandblast the frame, got sand in the differential and possibly the axles. All fluids have replaced and axles were cleaned out and refilled. All u-joints, front and rear drive shafts were replaced and have been rechecked. The transmission mount was replaced, it was the one out of the donor truck, but looks like it was torn during accident, so we replaced with new one.
All bolts in the suspension were checked. We are currently trying to bench bleed the clutch master cylinder and then will be re-bleeding it at the slave cylinder. The master cylinder was original and still full of fluid, so it was initially just bled at the slave cylinder. But, we are bleeding it just in case this could be the issue. Could this be the issue? If not, what else is there to check or what else could cause this?

 

Welcome to the forum

Bucking with 4.0l is usually dirty MAF sensor, quite common on the 4.0l
I assume you are using the 4.0l MAF and computer

Check carrier bearing on drive shaft, if its a two piece shaft, they can make banging noise like you describe when "jerked"

I can't see the clutch causing that jerking unless you were using it every time it starts to jerk

 

Yes, everything under the hood is out of the 4.0