OK im a " new " 93 4runner owner 125k. truck was running cold and could never get it to warm up ( or shift into OD ) i had to drive the thing for about 20 min before temp would get half way. so i changed thermostat only to find that previous owner took out the old one and left it open . now car heats up fine at idel , but when i drive it gets hot , what Gives. PLEASE HELP

 

Check the radiator, it could be plugged, maybe thats why the previous owner removed the thermostat because it was over heating.

 

overheating while running down the road = radiator stoped up. I bet one tank is hot to the touch and the other isnt. This means the coolant is not circulating through the radiator causing the overheating.

 

OK. sounds simple. but is it as simple as a draining it or a complete flush
Thanks for the help guys .

 

In this case I usually just replace the radiator. You could try flushing it first but I have found this usually doesnt fix the problem.

 

Well there you have it.. flush it and still gets hot when driving. guess its time to replace.