Multiple Causes for Service Engine Soon Light

[MikeatSD]

The Service Engine Soon light came on and I brought the car in to the dealer to diagnose the problem. After an examination of the computer log and the car they told me the following had to be replaced:
Oxygen sensor, 2 x ignition coils, spark plugs, temperature sensor (previously replaced 2 years ago) and that the engine needed a fuel injection cleaning. They also said that there was a log recording for the transmission, but it only happened once so I shouldn't do anything. I replaced all the parts that they told me to and cleaned the fuel injector. After driving for 10 minutes the light went back on. I brought it back to the dealer ($78 for original diagnosis and $78 to reset computer) to reset the computer and recalibrate. They now told me there was a code for transmission operation dealing with torque converter clutch. They did not know exactly what that meant until they could troubleshoot. But I was told it is an emissions system code.

Any suggestions? Should I bring it back for diagnosis? How is the service light reset?

Thank you.