rs6 power loss, new owner! HELP!!!!

[stevers6]

HELP please!!, spent savings and bought a RS6 3 weeks ago with Milteck and AMD S1 chip but it seems to have lost its "Punch" at about 2,000 rpm overnight. Before it would throw you over into the back seat but now seems to not really come on song untill 3 - 3.5 k rpm and doesnt seem as responsive. There is no undue or extra noises etc but just feels like someone has stolen the chip out the ecu overnight! Was left for a week while on holiday and the battery was low so jumped it from another car, didnt use jump pack. Ocasionally it sems to be back to as i bought it, but then goes back to this prolbem. Has full Audi history and covered 45k miles with last service 1500 ago so hasnt been neglected?? Just wandered if anyone out there has had or can shed any light on this problem or give the name of a good company you knows what they are doing