Just recently bought a 2003 Mazda RX8. Everything fine until I came to set of traffic lights about 10 miles from home and the engine stalled and I could not re-start it. Got towed home and then tried the car 24 hours later and it started first time. It drove ok for another 100 miles and then the same thing happened again after about 25 miles of driving. This time the RAC guy was able to re-start it with a jump pack and by removing the fuel pump fuse. Any ideas what it could be? I've made sure I've warmed the engine before I've left on any journey and each journey has been at least 10 mins long.

The RX8 is prone to flooding because the spark plugs on the leading side are so cold (heat grade 8) Mazda later introduced HOTTER spark plugs to aid the problem.

Try NGK iridium RE7C-L on the leading side and RE9B-T for the trailing. Here's an install guide which explains this in more detail - RX8 Spark Plugs

You say he removed the fuel pump fuse? Do you mean he changed the fuse? The fuel pump can't work without the fuse. Perhaps the fuse is blowing and causing the engine to stall and not restart. Find the fuel pump relay and swap it with another relay of the same type. Make sure the fuel pump fuse is good. If the engine starts, drive it around close to home until you think it's had time to stall out again. If it down'nt stall this time then the relay is bad and needs to be replaced.