Chrysler Repair: rough idle after timing belt repair, throttle position sensor, internal leaks

Question
I had the timing belt, water pump, blower resistor replaced on my 2002 Chrysler Sebring LX the mechanic said it idled rough but wanted me to drive it to check it out.  I drove it aboout 80 miless and checked the codes on the dash board. PO172. What should i tell the mechanic to do to fix the rough idle?

Answer
Hi Frank,
The code is saying that the fuel system is rich according to the rear upstream oxygen sensor. The possibilities are numerous and probably best checked in the order listed:
oxygen sensor heater
oxygen sensor itself
evap system purge solenoid
oxygen sensor circuit shorted to voltage supply
oxygen sensor signal open
throttle position sensor voltage higher than .92V closed
throttle position sensor sweep has discontinuities
MAP sensor operation faulty
engine coolant temp sensor operation faulty
engine mechanical problem (*might want to check timing belt settings for alignment of cams and crank sprockets)
fuel filter/pressure regulator (high)
pcm faulty.

I hope this will be resolved for you. Let me know if he needs any specific wiring assignments and tell me which engine you have.
Roland
*while there are many item under this "problem", the timing is the main possibility given the recent repair. Also check the egr function. Then:air induction restriction, engine vacuum to be at least 13", compression, exhaust restrictions, pcv system, torque converter stall speed, power brake system to have no internal leaks, plugged or restricted fuel injector, wires to injectors