downed compression on cyl. 3!

guys i have lost just about all compression on cylinder 3 only. we you scan it it comes up as a miss fire on the computer. when we did the compression test it showed up as 25 psi not the usual 150 like it should be. the plug is fine but with alot of gas on it and seems to look like maybe the exhaust valve? the plug wires are fine injector pulse is good and no exhaust leaks. what could be cutting down on my compression and causing my problem? its putting my trans in limp mode and runs like dog crap!! check engine light is flashing and traction control is going nuts!!! need your help cuzz she is out of commission till i get help??????????????????????????????/:hyper2::hyper2::hyper2::ugh2::ma:

rings?

Missing piston. Someone stole it:notme:

Yep, leak it down.

what do i need to do in order to leak it down? i have already done a compression test. it went from 150 psi normally to 25 psi. the dealership said that it could be either the valve has stuck open or the rocker arm is broken note that it is on the exhaust valve and not the intake valve. there is gas on the spark plug and the igniting is fine i have spark. the coil pack and plug wire is fine. they (the dealership) seems to think it is the exhaust valve is either burnt, stuck open, or the rocker arm is broken because they said that they have seen about 6 or 7 2007 trucks come in with broken rocker arms? also the truck will crank and run fine and unless you heard it everyday would never know anything was wrong. the only way you can tell is that if you give it some gas it sounds a little more loud or the exhaust pops a little bit? its never done that before?

All you need is a leak down tester, a compressed air source, and a spark plug socket and ratchet. It would also help to have a socket to turn the crankshaft.