RX7Club.com - Mazda RX7 Forum - 13b s4/5 turbo occasionally drop out on idle/ won't start

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Hello all,
Over the past couple of months I've had issues with the car dropping out on idle and occasionally not starting. Not everytime but enough to be somewhat a concern.

Sometimes I'll try to turn the car over, everything sounds fine but it just won't fire, if I spray some start ya bastard down the intake it'll generally kick over just enough to rev it out and then it'll happily idle and drive healthily.
Afew days ago I took it for a drive for 15 minutes, hit the freeway and it ran fine, full power, nothing wrong. I pulled over and hopped out the car leaving it to idle for 1 minutes and it dropped out, I tried cranking it several times with no luck, then I sprayed some start ya bastard in, it turned over , I gave it some good revs and then it ran fine all the way home, I have since started the car twice with no issue, it's very intermittent and inconsistent.

Pictured are the spark plugs I've taken out and cleaned with a wire brush and contact cleaner, it removed all the black build up but the striker? on the spark plug remained white coarse and calcified/ not shiny. Since cleaning them I've still had the same issue, do the plugs look like they require swapping?

Some years ago when it was serviced I was told the injectors were blocked / not working properly and they were fixed, could this likely be the cause?

The car runs fine, idles healthy.. when it doesn't cut out, and doesn't feel like it has lost any power, is it fair to say this isn't a compression/apex issue?

Thanks in advance