89 f150 with a 300 inch inline. just replaced valve seals and in doing so regasketed the top of the engine. head, valve cover, everything. before this i did a water pump, radiator, both hoses, and the head itself, it now idles at 2000 rpms and overheats. have no idea what the hells going on

 

This could be a few different things given the work that was performed....1st things 1st, remove the radiator cap (cold) and start and run the engine for 20 mins or so. See if there is any movement of the antifreeze thru the radiator.
Double-check the water pump serp. belt routing-is it spinning the right way or backwards. Its an easy mistake-the routing guide should be on the hood, IIRC.
As far as the thermostat, check it in a pan of boiling water.
Finally, get a meat/candy thermometer and place it in the open radiator, just to make sure that you are indeed running hot. Hope some of this helps!
Roger

 

thanks roger, ill keep that in mind when i mess with it again