89 Cherokee hard to start, idles fine, loses power on acelera

I have a 1989 Cherokee, 4.0, automatic, 4WD, with Fuel injection. The Jeep has 142,000 miles but the engine only has 23,000 miles. It is a Jasper engine.
I've owned it for several months. It has always been hard to start but other than a little hesitation on take off, ran great. It recently started losing power on acceleration. It runs good when in low gear but when
it changes gears, it loses power and has a slight miss and backfire. It has good fuel pressure and compression. Parts I have replaced are: fuel filter, map sensor, temperature sensor, air control sensor, crank position sensor, and pick up coil. Nothing has helped. I'm at my wits end and I appreciate any help you can give me. Thanks, Roger
PS: I definitly will make a donation on payday
because I probaly will be visiting this site often.

Could this possibly be a stopped up catalytic converter?