Scotty, my 87 Toyota PU has (only) 137K miles. It's got the 22RE with 4WD and automatic transmission. When I bought the truck 2 years ago I had the water pump replaced. When hot, the truck idles roughly and sometimes stalls. I've checked all the vacuum lines and when I checked the coolant level recently, the radiator was bone dry. Although there were no coolant leaks, I had noticed some white smoke from the exhaust. I checked the oil and it looked fine - no milky substance on the cap or dipstick. I went ahead and replaced the (original!?) radiator, thermostat, and hoses and flushed the entire system. I rented the leak detector kit you recommended from AutoZone and after doing it twice, it "passed" both times (the fluid stayed blue). I also put in a bottle of Bars gasket sealer. When I drive the truck the temp gauge climbs up above normal range after about 5 minutes. I tried burping the system again but it didn't seem to make a difference. I also still notice some white smoke from the tailpipe. I took the truck to a local mechanic who pulled the plugs and did a pressure test and found no issues. Do you have any idea as to what is going on? Thanks for all your generous advice and knowledge.