I was coming home last night and decide to "exercise" the car a little bit and when the car got around 100 mph the Check Engine light came on so i slowed down. i wasnt too far from home so i cruised home around 30 mph , when i got home i checked the code. and I got code 21 and 22. i went out after checking it and accelerated the car once again but got nothing. Then today i was goin to work and got to around 80mph and the same thing again.

what can be causing this to come on once and a while?

also another problem i am having is when i start the car when it is cold it idles around 2200 rpm, and comed down gradually after like 5-10 mins and then it idles at 800 rpm or so. i took off the FITV and cleaned it and screwed in the white thing tight put it back on, it helped because the car used to idle at like 3500 when cold. anything else can cause this?
how can i fix it ?
can i bypass the FITV?

and lastly when when i drive the car from cold it drives fine but if i stop and come back to it a little while and drive it sputters around 30-40kmph and 2000-3000 rpm, when i push in the clutch and rev it sputters pass and revs clean and the problem it solved. what can cause this sputtering but clears up when i rev it out ?