My car has recently started idling erratically. I can be driving along and slow down and the car will remain at around 2000 rpm when in drive, or if I shift to neutral it may go to 3000 rpm. Obviously raises havoc with the brakes and driving in traffic. The majority of the time it drives normally but about 25% of the time, lately, it will not return to normal idle after driving for a time, or (lately) even shortly after starting up. The transmission has been affected by the idle as well and, I want to baby the car as long as possible and make the transmission last as finances are a problem and cannot afford a new transmission. It is adequate nearly all of the time except recently. I have been out of the country for approximately a decade and not that familiar with fuel injection so not sure how to adjust idle etc. Or what the exact problem is. If it were an older car I would be familiar with it, but now. Well, I am not.
The local mechanic says he cannot even look at it unless the car is driving erratically, which is another problem. We have always changed oil on time, and were planning on changing the transmission oil this time as well. We have only had the car for 9 months so cannot tell history except it drives well except for this problem.
HELP, can you at least steer us in the right direction?