89 22R. runs good. wont idle

I have a 1989 toyota P/U 22R carb ...bought for $200. reall good condition for the age .... watched a new water pump and radiator belt be installed. so it over heated. cooling problem I'm observing. trucks sits another 3 days and the person is try to sell it to the wrecking yard. they say it's blown up. ok I'll by it for 200. ok deal ... so new rad cap new thermostat it was frozen the rad cap was blowing water out the top and water slightly out the tail pipe very hard to start. blown head gasket. put a over the counter. temp remday. in New spark plugs. water of course it runs. runs well good power too. "so plugs, rad cap thermo,stat new oil and 5 gals of gas. it was on Elvis. when I pushed it over. It won't idle I can keep it running. I'm getting a slight air pressure in cooling system dosent blow water out of resev. but bubles also it retrives coolant back in to the rad. and runs slightly past 1/2 on temp gauge any tips. I'm into it under 300. by the way good power and no hick ups through the gears slight hesitation from a start. thank you