i got 99 Toyota platz i bought it in 07 (automatic transmission) reading 70000 . Engine was working perfectly but yesterday i was sitting in the car and it was on at first it was running perfectly and suddenly RPM decreased and started jerking in park (P) . and when ever i start it now it start jerking from the beginning and jerks until i push the throttle more than half . What happend to it and what should i do to overcome this problem . last tuned a year ago does it require tune up or any other suggestion.