ok so my wife was driving our 2002 audi A4 1.8T today and suddenly it starts idling really rough, hesitating to accelerate and the check engine light flickers on and off. Right before this happened (we have only owned the car about 6 weeks), we got the oil changed with SAE0W-30 castrol synthetic oil @ oil can henry's and they ran their engine sludge reducer (gold eagle oil system treatment) through it before the change, we also had the brake fluid topped off by a reputable audi service location and the brake light switch and L shaped vacuum hose replaced. I'm thinking that the oil sludge treatment chemical loosened up some sludge and clogged the fuel filter.
Also, the car ran fine (better than fine actually, I noticed better acceleration and improved idle) for awhile after the work, then it sat several hours and then my wife ran to the store and that's when the symptoms presented. Any ideas? As I said, I'm an Audi newbie, but I'm feeling clogged fuel system...

 

You need to have it scanned to see what codes it it throwing. Some auto parts stores will give you a "generic" scan for free. You should try to find someone with a VAG scanner to get ALL the codes that may be stored.

The flashing CEL is typical of a misfire issue. Could be the MAF or a vac leak or coil packs or......YOU NEED A SCAN

post the results

 

I'm worried I shouldn't drive it. I left it in the parking lot my wife was in when it started happening.

 

i would lean more towards a clogged oilpick up line. Though the symptoms you are speaking of sound to be more of a coil pack. I dont think its the fuel filter as you will hear a strang noise coming from the trunk area of the car when u turn the car on. If your mil light is flashing and you are hesistating especially under load then i would say coilpack when out.

 

drive it to the advance or napa or autozone and check the cods, the only way you going to find out what wrong with it.. If its flashing it could be coils i just change it mine but i still drove it to the place just like it was running very bad.

 

Well, I feel silly. The first time I went to look at the car it was dark outside, that's my only excuse lol. But I went back in the morning and this vacuum line had popped off....I reattached and everything ran like a dream. Drove to the nearest auto shop and cleared the code, which turned out to say "cylinder misfires."

 

it was whichever line it is there in the picture that is on bottom. It doesn't normally have a hose clamp on it but I had to add one to make it stay put lol.

 

glad it was something simple