Volvo: gas mileage, low gears, misaligned teeth

Question
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Followup To
Question - why is my car getting lower gas mileage than it previously had around town.

My Volvo is a 99 GLT V70.  No there has been no loss of power, the air mass sensor has already been checked.  I do notice a vibration in the car at very low gears, when the car is downshifting to low gear or just moving at around 10-15 miles/hour (transmission?).  Could the automatic choke be stuck causing low mileage for the short trips I'm taking around town?  Is there a way of checking the transmission out or the timing belt without having to take it completely apart?

thanks again,
terry

Answer
Based on your description, my vote would be for a transmission problem before a timing belt problem.  The typical issues with a wrongly installed belt is misaligned teeth, which cause the car to not run at all, or run horribly at all speeds.  Given the car's unchanged performance at highway speeds, you can probably rule out the belt.  As for the transmission, it could be a problem with the torque converter which handles the load changes during gear shifting.  A problem there would be very noticable at lower speeds.  To diagnose a problem like that, you'll probably have to have a mechanic drive and assess the problem, as well as hooking up the diagnostic computer to check for error codes pretaining to a transmission issue.  With a car as new as yours, there's very little you can do on your own regarding the transmission.

I'm not sure what you mean when you say automatic choke, so I can't make a comment about that.

Good luck!