Let me be the first to say, ive probably had this problem longer than anyone here. 3 years of the exact symptoms your describing here and 3 thousand dollars later ive finally realized that my CLUTCH is to blame. Everything clicked yesterday on my 5.5 hour drive home. The car runs normally under light acceleration and constant speed, but when pushed up a hill or quick throttle response the car will bog down and start to hesitate. Im serious when i say that for three years its just gotten worse and worse for me. Im going to purchase a pt cruiser clutch within a week and replace it within a month. Im dead set on the fact that it has to be my clutch slipping...150,876 miles on an oem clutch must be its limit.