Ok, so important information there. Even the 150 had a MAP sensor that's open to the air, it still affects the map, just no to the same extent, and you are right it's for driving to the Alps :-), but unplug it and the car will run like a pig (on a stock 150). All bets are off if Steve G has worked his magic on your car, my information is based on stock setups. Given the above information, you need to restore your TPS to the value it was when Steve worked on it. That's the problem, and reason CC don't use TPS based maps, the map becomes dependent on the TPS value, and these are not all consistent. The ECU isn't capable to learning, so setting up becomes the important part.The resetting of the ECU is just something you should do every time any change is made, be that mechanical or electrical, so the ECU when starting has the base values, this can only be done by pulling to power (easy with a battery isolator). BUT There is one thing that springs to mind, was it raining on the way to the cambelt change? I have heard from the specialist that did my 150 conversion that the open to the air MAP sensor can suffer from direct water strikes. He recommended a small hose to make a U bend to prevent this, still open to the air, just not upwards. Since it's such a small expense I have done this to all the 150 club members that have come to me for a tune up. Never seen it myself so I only have that on hear say.