Truck misses at 1750 rpm

I have a 2003 TRD. V6 3400. Truck runs ok until hits 1750 rpm and falls on its face. Have replaced many parts and 5 different garages. Help!

 

What codes are active, or have appeared? What parts have been replaced? What did the five shops say?
Does engine sputter, or shut off abruptly??

 

Garage 1 plugs and wires- no difference. Garage 2 cam sensors no change. Garage 3 crank sensor and pulley no change. Garage 4 throttle body, injectors, and fuel pump. Garage 5 determined electrical, not fuel. At 1750 rpm goes down to about 3 cylinders.

 

Did they change any of the ignition coils. I know on my current F150 I started getting a lot of misfires even after new plugs. Turns out one of the ignition coils went bad. My mechanic said he even tested them all but they all checked out.

 

I did replace coils. No change.

 

Darn

 

The engine twists when throttle is applied. What are the odds that the movement causes a break in the electrical for that cylinder?

 

Man... why are you taking it to so many different shops? I understand you may not have been happy with the work performed, but you're really opening up soooo many variables. Maybe stick to the last shop unless you burned that bridge somehow. Introduce some consistency in the diagnosis and repair. No one wants to work on a truck that a million people have worked on. Issues like this are rarely one shot solutions- many fixes end up being applied and one of them ends up working.

 

Maybe ECU, could be failing or corrupted. Should be able to hook it up to a quality diagnostic that can ready live data and that should tell them exactly what and where it is failing.
A dead short or ground can cause this also. The old trick is to look at it when its dark with no lights on and sometimes you will see a dead short in a wire as it arcs out or goes to ground.