1997 f150 4.2 (V6) 2wd Extended Cab Automatic Tranny

I have noticed a ticking noise. It does not sound like lifters to me but i know nothing. Anyways the truck had been sitting for about 2 months and when i checked the oil yesterday it was about 1.5 quarts low. I put oil in it and it was fine. Today i checked the oil and it was ok so i drive it. when i started it i heard a ticking noise. It does not get loader when i give it gas but it seems to go away. That may just be the motor noise drowning it out though. Then while driving i noticed the oil pressure gauge was moving very fast up and down but only a very short distance. Then all of a sudden the oil pressure goes like all the way down for a half of a second then come back up to where it should be. When it did this the ticking noise got louder. It did this 3 times while i was driving... I have it parked now. I can start it and it ticks while it idles but if i raise the RPM's just a little then the noise goes away... what do you guys think... COULD THIS BE A OIL PRESSURE SENSOR PROBLEM?

update: It does not make much of the ticking noise when in park or neutral. When its in Reverse or Drive the rpms goes lower and the ticking is a little more noticeable.

ANY HELP AND RECOMMENDATIONS IS APPRECIATED...

Sounds like oil pump failing or internal collapse of oil filter and/or severe sludge build-up restricting return paths to oil pan. Deal w/ it soon. Check the integrity of the sender connector & wire first but that doesn't explain dry metal to metal top end noise.

I thought that if the oil pump failed then it goes out fast!.... like it would just stop working altogether? i am not sure thats just what i was told...

It definitely would be time to notify it's "next of kin" if that is the prob! I did mention other possibilities. A can of "Seafoam" in the oil is the best de-sludging agent. Then change the oil & the filter (don't overtighten). That removes 2 of the 3 potentials. The pump could be being starved.

I took it to the dealer.. they suggested that it was the main bearing was worn a little and causing the sound...... does this sound correct?