I'm driving expressway at speed of 80kph then suddenly i felt a bit of sudden lose of power and RPM dropping a little then my Check Engine Light started blinking. Then it was gone after 5 mins. Then it happened again when i was going uphill and gone again after few minutes. Next day i brought it for scan and they said they cannot scan because the engine light should be on for them to have a reading. They checked the spark plugs and said they are fine.

Does anyone here know what's the problem of my mazda 3 2005 model? when driving in city it doesnt happen due to my driving mild. But sometimes when idle my engine is behaving differently like it's shaking a little bit for few seconds.