Ford Repair: F-150 burning electrical smell, feels like misfiring., ford f 150, automotive electrician

Question
We bought a used 1993 Ford F-150, recently had the fuel pump, fuel injector replaced. Ran okay until 3 days ago. Driving on a major highway speed was approximately 65/70 then had to slow down to 45 for heavy traffic. It started lurching like it was misfiring, we got a burning electrical smell in the cab. We took it to a mechanics shop, they hooked it up to a diagnostic machine, said everything was ok. But still lurched and had the bad smell. They replaced the plugs, the plug wires, the cap and rotor. No help there. We're now 500 dollars into this, and the mechanics have no clue what is wrong with it.

Answer
Take the car to an automotive electrician.Sorry about the 500 dollars,at least now it's tuned up.Auto electrician's are little different than regular mechanics simply because they specialize in it.You just don't want them rebuilding you're transmission.The same can be said about regular mechanics doing electrician tasks.