I ahave a 1995 F-150 XL 5.0 L V-8with 179,000 miles. I was in Iraq for a year and my truck was driven occasionally but sat up for 3 months without being moved prior to my return. The first time I took it out it did fine for the first 5 or 6 miles. I began hearing a ticking from the engine and immediately pulled over. I checked the oil and water and they were fine. Upon restarting the ticking disappeared. Upon my return home it began again. Temp and oil pressure read fine so I continued the mile to the house. The next day I took it out again and after 7 miles it began ticking again. I turned around and the oil pressure began jumping from low to normal then went to low and stayed there. I pulled over and checked everything again. Oil and water fine. No leak noticed . The ticking is still there, but oil pressure is fine at idle. I believe there might be some kind of oil pump problem or blocked oil presuure relief. I am trying to locate my shop manual now. Any help is appreciated.