Wounded, but not DRT

[YoungBurb88]

Had some "funny" business going on with the Burb on my way home from work Tuesday for which she gave no warning whatsoever.

Backstory: Replaced Valve Cover Gaskets as the the valvetrain got a needed adjustment, spark plugs replaced before that, Oil Change and Trans. Fluid/Filter Change done before the plugs. After adjusting valvetrain, found out the Burb needs motor mounts, bought them and a full set of Sensa-Trac Monroe shocks while I was at it (hadn't had a chance to put them in yet). All of this was done between last Friday and Monday this week.

Tuesday: In rush hour after about 20-25min driving time she starts overheating, looses all get up and go, and oil pressure drops. Get her pulled off at the QuickTrip, after about an hour I check it; Has plenty of coolant, not leaking from anywhere other than the radiator cap, oil is fine... nothing looks to be wrong, so I'm scratching the head... head home from there, after about another 20-25min driving, darn near home she does it again and I just baby it to the house. After a couple hours I check the fluid again and everything appears to be fine...... to say the least I'm bewildered and don't even know where to start looking.

Any ideas??????????????????????????????????????????????????????????????