99 suburban valve mystery

[nailer36]

I bought a 99 suburban 100.000 mikes. Took it home drove it 2 days ran wonderful quiet and all. Got up day 3 started it missing and valve train rattling. Thinkin lifter went flat or something. No codes.
Pulled valve cover and most exhaust valve rockers way loose.
Never had this before loose almost an .125 inch of clearance when lobe is down. Not sure what happened. No sign of problem night before and it just started like this next morning. Any ideas would help. Mike

[buddy_1]

Check oil level and pressure. Low oil level can cause this. Low oil pressure could be caused by a stuck pressure relief valve in the pump. I've had a couple of them that the screen would stop up due to loose carbon build up floating around in the pan. Buddy

[nailer36]

Oil is fine working on taking intake off good time to change those wonderful gaskets before its a problem. Good oile pressure.
Thought i would get more than one suggestion, This one really has me will find out tonight or tomorrow when its all apart.

[nailer36]

K fixed and running great again.
Dexcool leaked into oil, no surprise there.
Oil became sticky and valve lifters got stuck.
Weird but fixed now.