I have a 1999 jeep Cherokee 4 liter 6 cyl & it

SOURCE: Power loss after running

loss of power can happen even if exhaust does not flow in other words you have a rstriction in the exhaust usualy the catalytic converter has collapsed any exhaust shop will be able to tell you right away, or when you loose power do you hear a hissing noise ? if so that is clearly a clogged converter replace the catalytic converter

SOURCE: 97 Jeep grand cherokee 6 cyl. idles down to 0 and dies.

any leaks in intake or exhaust upstream of the sensors, sparkplug condition and engine controls/sensors for out of range operation (including fuel pressure and condition of regulator)
IAC should be cleaned and checked as this can cause poor idle and shut down. I'm not saying not to change O2 sensors, but unless everything else if OK, it probably won't help.

SOURCE: 89 jeep cherokee 4.0 it bogs down and will accelerate in drive

Make sure that the timing is correct and that the spark from the coil is healthy. Problem can also be with the overdrive in the converter. If it's stuck on it can do that too.

SOURCE: I have a '97 Jeep Grand Cherokee Laredo 4.0 liter that won't idle

Check your throtle postition sensor. It monitors what postion the throtle is at and sends that info to the ecm. It will go bad and cause that problem.

SOURCE: Rough idle, sputtering, and backfiring.

try turning ur idle up its the pin on the throtle body just make sure u tuen the engine off and on again fter each adjustment to reset ur computer on ur engine