it would be best to remove the head.... its not hard at all. If you know how to turn a wrench then you wont have a problem. Could you go into further detail about the noise? does it sound like a bunch of marbles are in the motor?
3.0's are plagued with valve train noise, especially when the winter mix is out. It couldve been just that the rocker as loose that would make the noise. Which is interesting.... to be sure you can replace the lifter and if the noise is back its typical of all 3.0's ffv and non e-85. Try Lucus oil stabilizer that always does the trick. Dont change the weight of the oil just add the lucus to your normal oil change.
2004 Ranger S/C Edge
8.8 rear w/ 4.10
Flo Pro Twister Exhaust
SCT X-Calibrator 2 (Tuned by Boss 3.0)
Underdog Billet Aluminum Pullies
Rogue MAF Adapter
Morana 1.7 Roller Rockers
K&N Gen II FIPK