I'll shamelessly plug the AEM thermocouple interface/amplifier I'm currently selling.>>>
FS - AEM Thermocouple Interface/Amplifier
Guaranteed <1% accuracy at full scale...kind of important...
I bought it when using an ECU that didn't have this function built into it natively (my new Syvecs can accept K-Type thermocouples directly into the ECU). The AEM unit has 4x input channels (I only used 2 of the channels, an EGT on each bank on the secondaries), then fed that output from the AEM into my ECU as an analogue input. Worked like a charm, no setup and it comes with the voltage vs temperature charts so you can calibrate the ECU. Uses K-Type thermocouples. In as-new condition, aside from not coming with the 12w Deutsch connector which we needed for my install....easily available pretty-much anywhere.
(Can also output data as RS-232 for data logging into a laptop - I am half-wondering whether to keep the unit and use it to monitor "whatever", as-and-when I need to....all sorts of uses that it could be used for on a more temporary basis; stuff that you may not need to monitor on an ongoing basis.)