my dodge check engine light came on the other day it was a miss fire in cylinder 4,which was anything tune up..so i replaced the spark plugs which then the lights went off, then the temp gauge was all the way up and hot..so i replaced the thermostat...now i have everything back together correctly and tightned down but its leaking antifreeze pretty bad from around the thermostat area..i redid this several times and replaced the gasget a few times to thinking that was it any suggestions as to what it could be?