My daughter has a 2005 VW Beetle Conv 1.8l turbo automatic with 95k miles on it. A few months ago the turbo went out. I had it replaced within a couple weeks lights started coming on in the dash and the car would reduce to half power. If you stopped switched car off a few seconds then restarted everything would return to normal for sometime. I carried it back to mechanic the codes read throttle body he removed cleaned and replace the throttle body and everything went back to normal for a few weeks and then it started again. Once the cold weather set in it hasn't done it since. Today she pulled out of a shore and sped up when she slowed for a turning car her car did not down shift below 3rd gear. When she got to the next stoplight she switched the car off and it would not restart, it acted like it had no battery. A friend jump started the car and she drove off when she stopped at the next light the car shutoff and would not restart again. A cop and another guy pushed it in a parking lot. I went jumped the car off and drove it for a few miles with no issue. Once stopped I switched it off several times and restarted it with no issue. Any ideas on what could be causing my problems?