Hyundai Repair: 1999 Sonata rpms/engine problem?, replacing ball joints, diagnostic code

Question
I was stuck in traffic today and my 1999 sonata with about 95,000 miles on it starting acting strangely, and other than needing various replacement parts it has been running great up until this moment. I have automatic transmission. I had to hold the brake pedal down hard with my foot to keep the car from lurching forward and when i took my foot off the brake the car did just that. the rpms went higher than they should have been for being stopped and went even higher when i put the car into park. it happened in intervals, though, and would go back to being normal and then do the jerking lurching movement again. when i pulled over and turned off the car and then turned it back on the check engine light came on. i left my car for a while and returned to it to drive it home and it acted fine...no jerking and lurching and over-engine work. my mechanic just replaced the ball joints and aligned my tires (i don't think it's related)...but i guess i need to take it back in to him.  

Answer
The diagnostic trouble codes stored in your cars engine and perhaps transmission computers will provide the largest clue to the cause of your problem.  The fact that your check engine lamp illuminated indicates that the one of those computers detected a problem.

Any guesses I could make at this point would be very low in percentage compared to the speculation I could make with the aid of the stored diagnostic code.  You can take the car back to your mechanic, or you can take it somewhere to have the codes read and report them back.  In any event, I can think of no scenarios where replacing ball joints and tires and doing an alignment would cause this issue.