2000 A6 2.8 running problems- ARGH
 

Hello
new to the board, did a search and could not find what I was looking for. Got a running problem with a 130k mile wagon that has been the trusted daily driver till the trans broke. Went to a good local rebuilder (he has done plenty of them) and after I got the car back , it barely ran. Ok- found a big vacuum leak on the intake o ring being cracked. while in there, cleaned the throttle body, intake tubes as far as you can go, all new oxy sensors, new air and fuel filters. Have not tuned it in quite a while so new plugs, valve cover gaskets, plug wires, coil pack, fuel pressure regulator, fuel pump relay, and even a new fuel pump. Looked really carefully for vacuum leaks and no positive results after fixing a couple
Sure some expensive parts to throw at it, but I love how well this car handles and carries the two pooches around. Compression is excellent
Even took the cats down to inspect and the matrices look like new.

ok- so read the codes, cleared them, they come up again. P 1500 - starter circuit ? what is up with that?
The car idles horribly like it is about to stall. It runs really smooth as you hit the gas to accelerate moderately, but then while steady cruising at 40-45 mph 1800-2000 rpm, surges slightly back and forth< I think that may be the fault of the trans valve body . But before i give it up to the trans shop again , would like to take care of the lack of smoothness at idle (totally new since the trans build)

Any suggestions ?
thanks in advance