sportrak elxi 1.6 injection


Hello Group
My engine started pinking a little yesterday and the engine management system light has come on twice. I was struggling to get the revs over 3500 and going up a steep road was difficult. I got home and turned the engine off. When I turned it back on it was revving fine up to 6500 but then it came down to 5500 without me taking the pressure of the accelarator.
Any ideas as to what my problem is or how to remedy it would be gratefully received.
Many thanks