The cam sensor on that engine (as with all Ecotechs) is most likely the cause of your power loss (intermittent?) and the engine light coming on... These sensors are normally only £12-35 depending on the engine type and where you buy.. I'd suggest you have a look on Ebay for a decent parts supplier. If you have a friend or hubby who can hold a screwdirver the right way up then he can change the sensor without too much difficulty.
Stan
Edited the spelling mistakes lol
Stan
February 2008