P0303 Ford -

Question

coil checks out good inectors seem good throws code after about 15 to 15 mile

Answer 1

P0303 Misfire number 3 cylinder.

Check for proper connection especially at the fuel injector

 Here on this fuel injector , a misfire code kept setting at different times what was found is the fuel injector has a locking tab, with this the locking tabs where broken just by lifting on the injector harness the connection comes off easy, The fix was a use of a zip tie to hold it down