Emission control system on a 1999 Jeep Cherokee

Hello I am a master chrysler certified tech (jeep is built by chrysler) the problem you are having could be a couple different things the most common on your car is either the purge solenoid was recently replaced and installed incorrectley or if it was not replaced the solenoids were bad about failing and sticking open however I have also seen a larg number of cases where the vacuum supply hose cracked and fell off if you hear a suction noise under the hood while the engine is running this could be the case there are fairly simple tests for this part such as blowing through the fuel side of the solenoid while actuating it with jumper wires if your are mechanically inclined it wouldnt be hard to figure out but I would start by checking the vacuum supply to the solenoid I hope this helps if not you need to find a shop that has employed an ase certified L1 technician he should be able to figure this out very quickly as it is a simple problem and should not be expensive to fix at all