When I first bought my second hand 2005 mps 6 had the same problem develop and progressively get worse. even started to go into a safe style mode where couldnt rev above 1500 rpm or so without engine cutting in and out and i had to nurse it home. all sorts of lights where on. reset by unhooking the battery and it would be o.k. for 50 k or so and then start coming back. Took the intercooler off and found the coil spark plug cover on the far left was not on firm and when the dealer had the engine bay cleaned by detailer the chamber is quite deep and was full of water which was causing misfire problem and engine light coming on. took it to mazda and they steam cleaned the chamber as it started to rust the plastic bits somehow. then ran a diagnostic and did something on the tune and fixed the problem straight away. 10thousand k,s later and sideways at every intersection. have you washed the engine bay recently??? might be worth a look