Hi Just reading this thread and after having a very similar experience with a G Z20LET (Turbo) we found that once the car got up to temperature it would shut off - wait 10-15 minutes and it runs again. We also got zero codes out of opcom and snapon tools for this. So in Opcom you should have the option to run up the fans from the ECU's well the ECM module - our car has two fans pusher and puller which are very good at coolig things down. - I also cranked up the heater so I could feel if the heater matrix got hot - a reasonable test if its hot its hot

. So this was a pain to locate until I spent a few hours investigating. I was using Opcom able to run up the fans and check them to max speed (must have engine on to do this as they are power hungry) and they worked. Next used live data do not use IPC as that is not a great indicator and the fans should start between 95 and 100 degrees ours was according to ECM coming on at 97... Then you noticed it drop to 85-90 range in seconds so you can eliminate the fans as good. once it go to 97 with the fault the fuel pump cut out, no crankshaft output, no codes but it would crank. after about the third try with live data the car got hot and dropped a crankshaft no signal - so most likely suspect is crankshaft sensor (and yes have known these to fail unless you get a OEM or good quality one out of the box). You have the tools to work logically over this one and I would start with looking at the expansion tank (are you getting a good flow of water around the top, when and what coolant do you use - something clogged up?). run up the fans from opcom - at least you will know they work. Monitor the crankshaft sensor, then live data the temp - so do things slow and double check before you change things as that will just introduce more pain later. Please confirm the engine as well as you have alot of codes being kicked out that on our Z20LET we just did not get, in fact it was very quiet to say the least - the only concerning one you have is "Engine is Too hot" - so confirm if it is too hot - can you re-produce the issue? if so great if it comes and gose just monitor temperatures as this could be temp sensor - some cases these get oil in from leaking gaskets and are cheap to change as is a crank sensor - but I will say on a Z20LET Turbo is a pain to change. This can be - Water pump, clogged up due to rubbish in system, good old thermostat (you can take out and test) - the odd ball is even with a high temp (all fans should be going mad at this point with engine off even) the car should still run - and crank. So take time make notes and change one thing at a time. look for hot spots around car and where ECU is as well. - these have been known to fail when hot and cause this but I would start with simple things first. Visual check of all wires as well since they can get pinched - and yes RAC man told us the coil pack when hot can do this as well, so I agree you need to keep options open there. I am interested in where this goes as I know its painful to find but at least you are getting codes.
Check wires for Sensor - and change ask if your car is cold it should show as not reading very well (ambient temp) - check this with MAF temp as when cold should be close. - You have done in my view the right things so far just slow down make notes and have a break, think as logic will find this and do not rule out the obviouse (crap connector to the temp sensor - sticking thermostat).