110=120 is not very good compression. Should be 140-150, so rings could be your problem. As far a pcv, you'd have oil all over the engine, as the back pressure would force the oil out wherever it could get out. Hell, just change the pcv valve. Cheap item, and I'm sure it hasn't been done in a while? You didn't say if you changed it out. As far as only deceleration, no. You'll do it at acceleration too.

As far as the rag, they burn, so be careful. You shouldn't have to drive far with the loss you are encountering. Anything that can show you what is coming out is all that is necessary. I used the fine mesh screen as it will show a residue on itself if there is oil being burned. Your black tailpipe is most likely oil related. I'd bet on that over just carbon buildup. Try wiping you pipe inside up about 4=5 inches and see what you get out of it. I'm gonna bet that you'll get an oil residue, because of the sheer amount of oil you are using. Hope that helps some.

 

Gotta say man. Im super bummed... I've put so much damn money into this truck. Bought it for 2 grand a few years ago and have had nothing but problems with it. I have put like 2500 bucks into it to get it running nice then all of a sudden this happens.
I pretty much told myself that when the rings go I'm calling it quits..
I'm going to look into it a bit more but I just replaced the cats (600 bucks) if this is just going to wreck em again I think she's going bye bye.
Thanks for all your help man. Much appreciated.

 

And all this oil shenanigans just started like 5000 km ago.

 

It's really hard to throw parts at a high mileage engine, when you know in your mind, that as soon as you fix one thing, another is going to act up. It's the nature of the beast. Doesn't matter the manufacturer or brand.

By just changing out the heads, you brought out the next problem (rings ?). If you had done the rings too, then you would of done the bearings, and possibly the crank. For sure the timing chain and water pump, and on and on it goes. I know how you feel. Try being a mechanic and you pull the heads and find a burnt piston. Now it's replace 1 piston? Probably not. It snowballs to higher costs and more parts needing replaced. You shouldn't be to disappointed, as you have over 175k miles on your motor. To me, for a 4.2 v6, that isn't too bad. Also, with the miles you have on your truck, I wouldn't try using any (ANY) type of engine internal cleaners. You can (and most likely will) release sludge that will travel thru your motor and invariably will end up with an engine knock. One poster recently did this. (personally I hate SeaFoam, but that is just me. Give me a good 44K BG cleaner and I'd be happier)

 

Not to jack the thread but I have the same problem. I have a 2000 F150 with 5.4L V8. It has 85,000 orginal miles. I had done a normal oil change then some time later went on a trip out of state and on the way there the truck ran out of oil. When I got back I took it to a shop to have them check it out. They could not find any reason on why it's burning oil. Not in the exhaust, on the ground or any place they could find it. No blue smoke or anything like that. It was the PVC either. Any suggestions, it's starting to get annoying to have to babysit it so much.

I read the thread and noticed people asking about coolant. Mine is fine. I know that my intake manifold had a crack in it which I didn't know about but the mechanics found it when I took it in to figure out the oil burning issue and it has coolant leaking then but now its fine. They did a tuneup as well (all new coil packs etc) because apparently it has a missfire that I never felt.