Over heating issues.

[PeachesU]

My thermostat housing had been leaking a little bit so the other day I decided to fix that, now prior to this I have not had any over heating issues whatsoever. I changed the gasket and that was it, well it stopped leaking but now it overheats in about 5 minutes if I'm driving it and ten if its just idling. I put in a new thermostat and another new gasket and it still is doing the same thing. I haven't changed anything else so should I get another thermostat and try it or is there something else that I should be checking? Any help would be appreciated.