Hey everyone. Another year and I've put more work into this old 1991 D21 4x4 and the new batch of new parts includes:
Replaced out all vacuum lines.
all water lines.
radiator hoses.
New thermostat.
New water pump.
Complete change out of all fluids from differentials, radiator, engine and transmission.
New gas pump and new lines.
New fuel injectors.

Ok so that basically does it for all the replaced out parts including last year's replacement of all spark plugs, wires, coil, belts, sensors, alternator.

So now that I've got all that done, now I've got backfire at high rpms when I decelerate or shift down to engine brake.

Now when I first got this old heap, I was tinkering around with everything trying to learn it and one thing I did that I think I messed up with F'ing with the screw adjustment on the throttle body. I have no idea what that original setting was and no idea how to get it back to where it should be.

Does anyone think that could be the issue with the backfiring? (running a little too rich?) Does anyone know the procedure to resetting that screw to where it should be? Or does anyone think it's something else? Keep in mind there's nothing left to replace except maybe the timing chain and the oil rings on the pistons.