1995 Jeep Cherokee Country

I have a 1995 Jeep Cherokee Country 6 cylinder, 4.0 engine, 2 WD with 183325 miles. It has been running well until my check engine light turned on, then shortly after that engine started missing so we did a tune up but it didn’t solve the problem. It seems to miss worse when I go a steady 50 mi per hour. A few days later the engine began dying on me while driving, usually if I was traveling slow or idling. After it stops it will usually start back up within 15 minutes to an hour. It cranks fine but acts like it isn’t getting any fire. We checked the fuel pump and it read 40 psi. We also changed the fuel filter, put injector cleaner in the gas tank, checked all the wires and plugs but still have problems. Now my speedometer quit working. We took the car to an auto service to have the computer scanned and the code indicated that we needed a new speed sensor and temperature sensor so we put them on but nothing happened. Still no speedometer, quits while in transit, misses and rides rough. Any idea what could be going on?
Thanks for any suggestions.