idle issues-84-305 motor

car idles fine for half hour or so, then the idle goes up some...carb was rebuilt by me, gasket kit a while ago to combat this problem..to no affect...causes engine run-on/pinging real bad when you try to shut it off..idle solenoid is "ON" but not contacting throttle lever..i can lower rpm by forcing back the throttle lever but it returns to same high idle when i let go..its the computer controlled carb..so is it the tps sensor??,the mixture control sensor?? idle air bleed valve???? i have checked all the vacumm lines no bad ones....and a couple days ago replaced the 02 sensor..so what gives???

car idles fine for half hour or so, then the idle goes up some...carb was rebuilt by me, gasket kit a while ago to combat this problem..to no affect...causes engine run-on/pinging real bad when you try to shut it off..idle solenoid is "ON" but not contacting throttle lever..i can lower rpm by forcing back the throttle lever but it returns to same high idle when i let go..its the computer controlled carb..so is it the tps sensor??,the mixture control sensor?? idle air bleed valve???? i have checked all the vacumm lines no bad ones....and a couple days ago replaced the 02 sensor..so what gives???

its a lean idle/more air than should be. Finding what part of that equation translates to reality is a challenge. Could be a vacuum leak, or a valve that control air consumption at idle. Feedback carbs aren't my speciality personally, so I won't comment on that aspect, but its definitely a lean/too much air issue. If it only happens after it warms up for a while, might be related to a thermostatic vacuum switch.