I have a 2002 3.5 trooper it has started running bad on startup throtle going up/down until it stalls. If you hold the gas at about 2000rpm you can here the engine smooth out. The code was po101 mas air flow I replaced it same thing after about 1 mile replaced again same thing went to a dealer. He replaced it again with a new one instead of arebuilt the same thaing again. The other code I get is 172 and 175 rich mix bank 1and2. I have replaced the throtle position sensor on the engine not on the gas peddle. Checked the map sensor against a new one with an ohm meter and got the same reading so I left it on. Gas milage is down exhaust pipe is black when you step on the gas it doesn''t blow black smoke. Also computer has been replaced when dealer tried to flash it and locked it up so had to install a used one. Thanks for any help in this Dan