No oil in the top of the engine

[jpnc]

I have a 1988 TBI 305. I looked inside the valve cover and it's not oiling ( just where you put the oil in at) .I haven't taken the valve cover off yet. I can see the push rod and rocker arm and No oil is coming out. I have 60-65 lbs. of oil pressure when I start it and 60 lbs when I drive it. Idles around 20 lbs.

It has 168,000 miles on the engine. It runs good. I'm thinking a cam bearing may be the problem! I have too much money in the truck to rebuild it.

Any ideas or what should I check ? The lifters are not making a loud noise yet. I'm scared too drive it. I don't think the strainer is stopped up. I drained the oil and spray 2 bottles of throttle body cleaner in the drain plug. Hoping too break up any build up on the strainer. I would like too keep the truck if I could fix it real cheap!

Thanks for any help!