Ford Repair: Blowby, oil filler cap, vacuum leaks

Question
I have a '78 F-150 with a complete overhaul several years ago. It has the 300 CI six in it. I aquired it after my fathers death in '05. He drove it rarely prior to '05 and since then it has a pretty bad blowby that is so bad that it fills the air filter with oil and uses oil too. All plugs are burning clean and there is no skipping in the engine. The engine idles and runs hiway speed quite well. I remove the oil filler cap while the engine is idling and and increase the rpm's and a lot of oil vapor comes from the inlet on the valve cover. Its a daily local driven vehicle with no blue/black smoke coming from the exhaust. Also, moisture on the dipstick, but not too bad. Thanks.

Answer
check pcv valve and hoses-i would replace pcv valve and check hoses to make sure they aren't clogged or sucking together-also make sure you don't have any vacuum leaks-


if pcv has good vacuum then it should be ok-run a compression test on all six cylinder and see what readings you get-