My son had a 91 Wrangler with fuel injection and my daughter had a 91 Cherokee also. Both were fuel injected. My daughters had a Jasper remanufactured engine in it that had almost 40,000 miles left on the warranty. Her jeep had 3 different modes of running,.........excellent, fair & poor. I went through everything I could think of & did a complete tune up with new plugs ,wires, cap, rotor, coil, fuel filter, air filter, and checked the timing and checked for trouble codes,(none). I ruled out injectors because when it ran good, it ran great! It never went away. Had a professional shop diagnose it and they put it on their dyno & even checked for blockage in the converter; again , no soap! Just before we traded it in on a 98 Cherokee, I tried to get a replacement PCM. It turns out that the problem was the vehicle had the wrong one. We found out the change over year was 93. It was wordage in the aftermarket that was the problem. It was supposed to be 91 & up to 93; (not including 93). I checked the info on the unit and sure enough, it was the wrong one. Too late, we had already put a down payment on the used 98 which ran up to 287,000 before she got another one! So, long story short, it may NOT be the problem, but be advised that the year of the unit can make a world of difference.