All winter i was driving car pretty slow. Hardly ever going over 4000rpm.
So today i jumped on highway and was driving 30min keeping rpm between
7.5k and 8.5k
I burned about quarter of tank hehe

At the beginning i got blinking cell when i was cruising at 8k rpm.
I shifted to 6th drive a little and CEL was gone. Then back to 3rd gear
I did 2 times and 2 times i got blinking CEL. After that no CEL and 20min at 8k rpm without a problem. I got Engine Coolant Level Warning Light like 5 times - guess have to fill up more.

Car now runs smooth and got very nice idle

So question is do i need new spark plugs?

 

Cel is from misfires. No big deal. Glad you are cleanning out the carbon.

As long as the cel doesn't stay on your good.

 

Coil/plug misfire. Start looking at getting some new coils/plugs in the future.

 

I'd also recommend doing a seafoam or "zoom zoom" cleaner treatment in the near future.

 

I did last year. I'll do it again when it gets warmer

 

misfires can be many things, but when it blinks, your coils, spark plugs, and possible carbon built up can be the problem, get the cleaning kit at your local Mazda Dealer for $25 or buy it online for $20, it's simple and easy, plus the seamfoam treatment is also good, but also try Red Level Cleaning Kit, you can find it at Pepboys or Advance Auto Parts for $10