Not the smallest list of things to work thru mate, but some things only take a few minutes to check.
Im actually thinking now that a Vacuum hose leak is quite possible... and this would cause it to run lean, and could create the same problems as your having.
Also the lambda sensor can get 'tired' with age, and can cause poor fuelling... any electrical tests you wanted to try, just PM me and I can write you out instructions of what to test and where etc... you just need a multimeter for most.
Hope you find the problem mate.
Nize.