blown head gasket?

2000 ZX2 92K

Thusday i installed a defective temp sensor everything seemed normal, temp guage working again and check engine light no longer lights.

About a hour ago a rollback was unloading my son's ZX2 in our driveway. He said it started missing+loosing power and noticed lot of smoke coming out the exhaust [ but, check engine light never came on].

I checked fluid levels [all normal] and started car..i let it run long enough fot the raditor fan to kick on [temp gauge almost half scale]. Everything seemed fine.....ran it up to 2500 rpm and finnaly got the white smoke. Of course everything is closed for the weekend now so i can only speculate [i know it's a gasket from past experince].

1. any relationship possible with temp sensor?
2. is there a outside chance a "sealer" could work[i'm not up on ford heads/gaskets]?
3. since it's a dual cam i'm not going to chance letting anyone other than ford replace gasket[if it comes to that]...anyone have a cost estimate?

thanks

Could be an intake gasket also.