I recently purchased a jeep from a friend. it had transmission problems but I had it replaced. it worked fine for a few days then gradualy began to drive more sluggish. i get hardly any accelration at all and when i do its uneven. the gears seem to switch smoothly.
Also to keep in mind
- it had sat for almost a year
- it has a bad catalytic converter

the engine was rebuilt about a year and a half to two years ago.
I have tried fuel additives and hi octane fuel to try n clean out the fuel injection but no luck on the first try.
suggestions?

1996 jeep grand cherokee laredo est 70k miles 4.0 v6 automatic