94 lesabre, hesitation starting and driving

hey all...last week my 1994 lesabre simply turned off while driving down the road at 45 mph. i was able to pull off and get it started again on the first try. but since then, ive noticed a bad hesitation when shifting gears (auto trans) and that it does not start very well, usually takes at least two tries, sometimes 3 or 4. the service engine light comes on as well when driving after a little while. i took it in to the shop, one that was highly recommended to me, and they told me it was the fuel pump, and proceeded to change it out. 412 dollars later, it did the exact same thing later the same night after picking it up. SO at least i know its not the fuel pump! i had a recent oil change, but not sure the last time the transmission was serviced, i bought it from a family member many miles away this past december. it has 78k miles on it. let me know if you have any advice! thanks!

Did you pull the codes when the check engine light came on? IF not, do so to help narrow the suggestions.