P0451 FORD - No service engine light

Question

I have a 1999 Ford Expedition with trouble code P0451 FORD - There is no service engine light with the code. Although it does come on with key on engine not running it goes off with key on engine running. The truck has a slight misfire and occasionally dies but restarts. Very occasionally it will die and not restart. I initially thought it may have been a coil problem. But the only code is for the evap pressure switch. Since this is an emissions code shouldn't the light be on at all times? Could this be a ECM ground problem. Or are there any TSB's on this problem. Any help would be greatly appreciated

Answer 1

P0451, the definition for this is , evap pressure sensor, but Ford list this as intermittent ignition concern, So you are right in a ignition  coil concern, The trouble shooting tree is to test the ignition concern staring with the harness then the coil itself,