Stalling. Took to mechanic. Replaced mass oxygen sensor. Did all tests available to him.
Start up-drive 40 miles-outside temp 90-car stalls. Turn off-wait 5 minutes-start-drive 5 minutes-stalls. Repeat 5 min rest, 5 min run, stall. All in 90-94 degree temp. Temp drops to 60 degrees in evening (in Montana where weather does that.). Car runs fine drove 60 miles, gained 2000 feet elevation. No problem.
Drove in heat next day. Repeated above. Mechanic says he is reluctant to replace fuel pump ($700.00) because he can’t guarantee it will prevent stalling.