91 n/a spitting after running a bit

[mnrthrt]

while i was on r&r i drove my 7 every day. for some reason my girl is driving it at home and after about ten minutes the cel comes on and she can't give it gas without it stuttering and not going anywhere. if you accelerate extremely slow its fine. if you turn the car off, wait about 3 or 4 minutes it comes on and runs perfect even dogging it but then the check engine light comes on again and it wont run for shit. no mods on motor other than an air filter replacing the box. it was on there when i bought it. anyone got any ideas? has new spark plugs, fuel filter.