Sounds like the MIXTURE GATE isn't opening all the way. Most modern gates are electric with tiny motors that open the gate. However Jeep has been late in changing from vacuum gates. Check the vac hose that goes into the firewall to see if it has a crack or even has become unattached.
That 2000 might even have the lectric gate which is easy to replace.
I had one ride that had a 30.06 shell stuck in the gate...once removed the gate operated normally again.
Big Jim <img src="/forums/images/graemlins/pfft.gif" alt="" />

professional bovine relocation specialist