Whats wrong with my D16a6 motor??? Rings or valves?

I need some tech heads on this one..Ok well my motor just broke 10,000 miles, It was FULLY rebuilt Nov. of 2002 last year. A couple months ago I did a compression test on the motor..240 psi on #1,3,4 cylinders cept for #2 cylinder with only 150psi!! Thats almost 100psi loss!. Now I am wondering how this could of happened, I have milled the head,honed bores, decked the block, 3 angle valve job,new pistons/rings,hot tanked head/block+++more...there should in no way be some kind of a leak happening.

I am pointing my fingers at the rings or valves. My car is only doing 15-20mpg and it seems to be getting slower as time passes. It doesnt smoke, but burns very little oil(rings?). Altough the motor purrs like a kitten with smooth idle. Now how can I tell if a valve is stuck open? I don't believe that bad piston rings can create such a big loss on compression but i do believe that a open valve can. Is there a way I can do a at-home leak down test?? I need to get this fixed as soon as possible.

Your chilton will tell you how to do a leakdown test, to determine if it is valves, seals, rings, etc.

the valves could possibly be out of adjustment.

If you do another compression test, you can try the bad cylinder dry, then squirt a bit of motor oil down into the bad cynlinder via the spark plug hole, then try it again.

If it's the rings, the oil should drip down and help temporarily seal them better, and the compression should go up noticeably for a little while. If it's the valves, obviously it shouldn't change.

An easy and quick thing to try

If you had a valve stuck open, wouldn't your piston hit it? It seems like that would be an obvious problem...

the valve wouldn't be stuck all the way open, just enough to not get a good seal. In most cases that i have seen though, a stuck valve would register 0 compression.