I just ran a compression test on my 91 bronco with the 5.0 and every cylinder was over 100 but at start up and as it warming up it puffs out a little bit of smoke. Then if you rev it up when you let off of the gas it will puff a little smoke. Im also getting lots of blow by and it wrecked my air filter and covered the frame and everything near the air box with oil. I already replaced the pcv valve. The one thing that i did find was a broken spark plug but every plug seems to be burning good. So what can it be? i thought at first a bad valve guide but its getting blow by and smokes even after the initial start up. It also seems to be lacking power on the high way and hard to keep it at like 70. I swear it use to do it fine even with the 37s and factory gearing but i havnt been driving the truck as much as i use too.