Re: Worrying loss of power!
could be a few things, coils possibly, air leak on the inlet, spark plugs. Could also be one of the many sensors. Someone with better knowledge might be along soon to help.
I would check the inlet air hose to make sure there's no splits or loose connections, and give the throttle a clean using carb cleaner. (be careful if it's an electric throttle, don't touch the butterfly just spray it well with the carb cleaner). Also you could take the top cover off the engine (you'll need large torx bits or ribe bits to do so) and examine the coil packs to make sure you can't see any splits, you can also start the engine and watch the coil packs to see if they're arcing at all but just don't touch them with the engine on as you'll get a nasty belt.
< Rob >
Spider 2.0 TS 1997
156 2.0 TS Selespeed 1999 (now sold)
147 2.0 TS Lusso 2002