ok im new here but not new to working on cars.
i have a 1997 a4 v6 manual trans, runs great, no appearant problems
other than the CEL dtc says P0173 fuel trim malfunction... seems to be the only code comiing up the car stumbles intermitently, weather driving or at idle, doesnt feel like a missfire. feels like the idle drops to low. open to suggestions. any help is apreciated.

 

It should be fuel trim bank 2 with a p0173. I would check vacuum lines for any signs of cracking , check for any pending codes.

 

yea ive been searching for any loose hoses replaced them all. havnt pulled the intake off tho, are there any vac lines under it?
no pending codes or i cant see them with my scanner. the car also intermitantly cuts off
at idle, at least when it warms up. then sometimes it starts right back up, and other times after it cuts out it starts then cuts right off. im stuck...

 

Does your scan tool have data stream? If so monitor the fuel trim values as a general rule of thumb they should be +10% to -10%, that's not set in stone but its a good guideline. Then while watching Tue fuel trim sparingly spray Carb cleaner spry(it is flamable) around suspect areas, you should be able to observe a change in the fuel trim if you have vacuum leaks. Also there is a vacuum diaphram near Tue throttle body with a rod coming out of it that connects to the throttle, take the vacuum hose of and spray some WD-40 into the diaphram(it repells water) and compress the diaphram a few time with your hand. Those diaphrams tend to get stick sometimes in my experience.