P0303 code; help needed

[TippsTheFoo]

Guys,

I've been dealing with this code (P0303 cylinder 3 misfire) for awhile now, make changes and it eventually returns. Obviously I'm not fixing the root cause. Any help is GREATLY appreciated.

What I've got:
2000 Explorer 4-dr 4WD 4.0L OHV AT

What I've done:
1.) New spark plugs
2.) New wires
3.) New coil
4.) New fuel filter
5.) Fuel injection cleaning
6.) MAF cleaning

Any ideas on what it could be? O2 sensor(s)?

The last symptom is on Sunday I started it up and it idled rough, but smoothed out (no check engine light). So, I drove it that day. Then on Monday I started it up, no (or reduced) rough idle but after a 1/4 mile the check engine light turned on. Tue-today it has been driving fairly smooth but the check engine light remains.

 

[TippsTheFoo]

Spoke to some guys here at work and they suggested I swap the fuel injector from cylinder 3 with another and see if the fault follows the injector. If it does then we know the problem - bad injector. So, that's my next step...

 

[RJDriver]

Subscribed..... keep up with the posts so we can follow along at home