More coolant = less cooling??

[ThespecialistKC]

Hi All,
About 2 years ago was fighting a cooling issue. Replaced everything, radiator, water pump, t-stat, hoses, radiator cap, temp sensor, heater bypass valve, fan and finally the fan clutch (which was bad and fixed the problem). Rock solid since then.
Last month or so started smelling faint coolant smell when driving. Past weekend after changing oil, traced leak to loose hose clamp at heater core. tightened clamp, leak fixed. Checked all the fluids, radiator down about a quart. Topped off.
Few hours later take kids back to ex's house, notice antifreeze on her driveway. Popped hood, appears coolant came from underneath radiator cap, but didn't make it to recovery tank. No leaks found elsewhere. On drive home gauge oscillating between "n" and "a" in NORMAL on gauge. For 2 years has ridden between "n" and "o".
Swapped t-stat that evening, using a non-cheapy 198 degree. No change, same temp swing. Did some research, decided system needed to be burped. Burped last night using funnel method. Got just a few bubbles, nothing major. Still have problem, perhaps with just a bit less temp swing. Any ideas?
Totally baffled why it would cool fine down a quart, but has a temp swing when full.
TIA for any and all help.

Oh yeah, bone stock '92 XLT with 200k on the clock.

 

[wood1]

Have you had to add coolant since?

 

[ThespecialistKC]

Not really, had to add some to the funnel when I burped it 2 nights ago, but other than that, no. Radiator was full when I burped it 2 nights ago.
When I run the heat it comes and goes (meaning it get hotter than cooler), so it seems like there is still air in the system, but dang if I know how to get it out.....

 

[1991explorerEB]

mine is doing the same thing. but on mine its leaking from the lower radiator hose.

 

[wood1]

I once had to burp an old E-150 by slipping one of the heater core hoses off slightly when it was running. Mind you, only do it to a cold engine or it could make for a really bad day.

 

[cogs]

didn't see that you replaced the rad cap (again)? also, mine leaks on the radiator right at the tube fitting beneath the rad cap. i put some rtv in there, and it doesn't seem to leak anymore.