996 Carrera - Shuts down

[Richardson]

Hi I need advice.
This problem is intermittent but consistent.

The car will start normally when cold, run normally for 20 mins, attempts to restart fail.
Maybe 20 or so minutes later, the car will start normally and the same happens again after running normally. repeat repeat

Because it's intermittent I haven't been able to check for spark (I'm usually alone).
I have checked connections to the fuel pump as well as replacing its fuse and relay.

I suspect the fuel pump but has this happened to anyone? Are there any suggestions before I invest in an expensive pump.

Thanks

[Richardson]

I should add the there aren't any fault codes, current or stored - the engine check light is off.

Reading some posts suggests the crank pulse sensor may be the problem.

Give me a proper failure - intermittent ones are .......

Did I mention?

Year 2000 996 3.4 auto RWD coupe.