I know the problem has been solved...but I thought it might be proper to add my $.02.
Fought similar issues on my '93 LX with 2.3 engine (yeah...LOL). Overheated on the highway but in town, perfect. Changed the stat, changed the fan, cleaned radiator, at that time removed the condensor thinking that might help but no. Replaced the stat again thought maybe I got a bad one. Put it all back to stock and was ready to sell it and a guy I worked with at the time turned me to a different stat. Robertshaw. The only stat I'll ever buy again. Not any more $$$ than the parts store garbage, made in USA, works like it's supposed to. Guess what else? MPG increased with the proper stat in it.
Just thought I'd throw that out there....I thought I heard once that Mr Gasket was a repackaged Robertshaw but I did not look at mine when I bought it (the Mr Gasket T-stat) so I can't confirm.