Help fellow brick boarders:

Purchased 99 s70 2 years ago with 76k. Received a notice from Volvo North America in May 2009 stating that the ecm upgrade had never been done. The check engine light had come on about a month before I received the notice so I thought this could be the reason the light came on. Mileage 101k.
Took the car to the dealer ship in June and had them do the upgrade along with replacing timing belt, new motor mounts, sway bar links etc. $ 2k.
After driving the car for about 2 weeks the engine light came back on and the car seems to be hesitating and runs extremely rough.
I took it to my mechanic and he told me that there were 3 codes that were causing the problem. p1017, p0455, and p1620. He told me that Volvo has been aware of ecm issues and suggested that I contact the dealer because these were codes related to faulty ecm unit.
I contacted the dealer, and was told that the codes could indicate a faulty ecm unit but the warranty had expired on my unit because the car is over 10 years old. I have 110k on the car.
Any advice would be appreciated.