[pontiacg6gt]

I have a 2007 pontiac g6 g.t. convertible 3.9 liter v6,... it was in an accident & now fix back and running, however it has a slight problem, some times the check engine light turns on & also says , engine power reduced & services traction.
when car operates in this mode it runs very slow & transmissions shifts roughly,.. some times it clears by it self & sometimes not !!!
what do you think is the problem here ???