Chevrolet Repair: spontaneous transmission problem, chevy malibu, coolant temp

Question
I have a 99 Chevy Malibu with about 25k miles. This morning I took my car
into the shop for a check engine light. The car was driving fine, I thought
maybe just a gas sensor, no biggie. At the end of the day they told me the
diagnostic test coded for a new gas tank cover and a coolant temp sensor. I
drive the car less than .5 miles and the car kicks very hard when I take off
from just changing gears. The car also kicks while driving but much less
severe. Furthermore, my temperature gauge no longer works. I took the car
back to the shop and as I expected they said they didn't do anything to cause
this problem, even though the very severe problem was non-existent when I
drove it in. I left the car there because I didn't want to further damage the
car. They said they would check it out in the morning but that I would need
to get a transmission flush. Please help. I have never had this kind of thing
happen to me.

Answer
Hi Yvonne.... well i would be looking for a new shop.... first off if they replaced the temp sensor, the new one must be diffective. second... the scan tool will not tell you it needs parts, it will only tell you what systems are malfuntioning... it is up to the tech to test the system to see what the problem is... the light comming on for the gas cap is a common problem... probably all you needed to do was remove it and reinstall it making sure that it clicks when you have it tight... the engine light will come on if the cap hasn't been put on right and will usually go out after it has been reinstalled right and after a tank of fuel.... The trans problem is something else... the shift for the trans is controlled by the computer... when they were changing the temp sensor do they unplug something and forget to hook it back up, if you believe that they have misdiagonsed the problem i would seek out another shop and get another opinion...if you wanna find out who is good in your area ask the local parts store or BBB...the parts guys usually know the shops that have the best reputation...hope this helps.... Merry Christmas