i'm hoping you guys on here could help me out with a problem--last night while driving my mk4 golf gti turbo the engine stuttered at around 60 mph and the engine warning light flashed on and off a few times, then went off, and it didnt feel like the engine was pulling. then this morning it struggled to accelerate in 3rd gear between 30-40 mph but since then it has been ok. what could cause this?