The throttle body may accumulate an oily, black residue in the bore and on the throttle plate causing hard starting or possibly stalling when coming to a stop. The throttle body should be cleaned during regular maintenance but do not spray cleaners directly on or at the throttle position sensor (TPS) as this can damage the sensor.
Engine Performance Problems Due to Residue on Throttle Bodies on Jeep Wrangler
Average mileage: 166,500 (90,000–243,000)
Exhaust & Emissions affected: 2.5L 4 Cylinder, 4.0L 6 Cylinder
20 people reported this problem
2003 Jeep Wrangler 90,000 mi, Visitor
I have not found a solution