After a trip to the local small engine repair shop (ouch!), got the mower back and was running very rough. Shop mentioned that the intake air manifold gaskets were probably the culprit. I appreciated his advice, but wasn't impressed with his re-assembly. Needless to say, for the money I spent, I'd been ahead to buy a nice cherry picker and do the work myself (I know, I know, you all said as much).
Irregardless, I bought the two gaskets and while the manifold/carb was off, I disassembled the carb and gave it a thorough cleaning, checked the fuel pump, replaced the fuel line from the pump to the carb and cleaned the manifold. Replaced all then fired her up. VAROOOOM! Running smooth now. Finished the work about 9:30PM last evening (well after dark) but did a test run mowing a few strips, then thought, "Heck, it's supposed to rain tomorrow anyway." I just continued mowing for the next hour or so, finished up about 10:45PM. Sure the neighbors appreciated it.
Only thing was that after running it for that time, I shut it down, then tried re-starting it. While cranking, a white plume of smoke came out of muffler; unusual. It finally started and cleared up. What could have made it smoke like that?