OK this is possible a good lead. Means to me that your starting fuel mixture is rich. The sensor is OK as when you heat it up this automatically reduces mixture and improves starting.

Some causes for rich fuel mixtures could be as follows:
Injector leaking?
Blocked exhaust?
Blocked air filter?
Too much fuel pressure (faulty FPR, vacuum leak causing the FPR to add more pressure) ?

Is there a cold start injector in addition on the 944's?

Just an update for you all - seems to be fixed.

I decided to put a a new temp sensor in, whilst the old one was still reading within specs and apparently working, it looked old and so i thought it was worthwhile replacing it. Also, took off the AFM connector, tested and cleaned both (was quite clean anyway).

Car is now firing fine from cold, hot, and is not stalling.

Took a last reading from both new and old temp sensors before putting it in - at room temp (about 70oC) new sensor was 2.2k, old was 0.8, so something now not right with the old one.

thanks for all the help.

Matt