Audi a4 2.5 v6 avent quttro esp light comes on at about 50mph and goes out when slowing down

your ignition switch (the electrical side) is failing!

take to a audi garage befor you do some expensive damage

AWD vehicles likes its tires to be within 1/8 of an inch wear difference. Uneven tires cause problems with the transmission and drivetrain. ESP traction control with its speed sensors etc: could get varying reading with tires of different thread wear.

change the MAF mass air flow sensor GBP30 on ebay

And the codes were...?
The ESP gets input from a few sensors - ABS wheel sensors, yaw sensors, MAF...
If the 2.4 has electronic throttle (it should), then there shouldn't be any form of actuation in the footwell, so can't help you with that one.

esp light comes on after driving for few minits and goes out when i slow down can any one help audi a4 2.5 v6 tdi 2002

ESP means Electronic Stability Program. When piloting an Audi TT if you enter a corner too fast for road conditions (wet or snow or mud) and suddenly let off the gas to slow yourself down (which is what most people do) you will experince oversteer. This simply means the back end of the car will slid out and point the car sharply into the corner as the front end trys to swap places with the rear end. ESP will try to save you by electronically applying individual brakes to individual wheels to get the TT pointing the right way. ----------- This will help.Thanks.Helpmech.

check if there an old leak..the oil light come on if low or high..but most likely you have an oil leak some where...if not..than it must be the oil pressure sensor not give the correct reading....

I had the same issue with my '05 A4 1.8T.  Turns out it was the RPM sensor.  Audi tried to tell me it was teh fuel pump and the cam-shaft positioning sensor.  Paid for teh fuel pump replacement and it died 6 blocks from the dealership.  Then they replaced the RPM snesor, works great now... Except it's still an Audi.

I believe that is a V6 engine? Firing order is usually 1357246.