Ford Repair: oil pressure, deal alot, crank case

Question
85 f250 351w/at.I am an euro mechanic and don't deal alot with fords but I got one thats itchen to be fixed. this motor starts up and has oil pressure for about 30 secs. to 1 min then it begins to fall off. I flushed the crank case and installed new oil and filter, but it is doin the same thing. I pulled a valve cover to be sure I had open drain ports in the head and thy're good. with the valve cover off I started the motor and watched oil run over the rockers, then after about 30 secs, it dropped off. Now that leads me to believe that I may have a clogged sceen on this cold runner.or the pump is goin' south. I heard fords have a oil pump problem, so when I drop the pan to clean it should I also get an oil pump and just put it in.   
any info would help! thanks Jeff

Answer
Hello and thanks for the question...I'll try to help.
 Yup, you'll have to drop the pan, but should be able to get a new pump installed. Before going nuts, might I suggest that you fill your opl pan with diesel fuel and let it sit for 3-4 days......let it eat the crap in the screen if there is any. About 1 1/2 gallons should do the trick. Drain the engine and clear it of the diesel fuel and add oil.
Use this link for pan removal:

http://www.autozone.com/servlet/UiBroker?ForwardPage=/az/cds/en_us/0900823d/80/0...


Hope this helps,
Erik