"The "uphill" symptom is likely due to a rolled-up ball of Cat innards, like I had on my '87. The "cat ball" would roll back on acceleration, partly plugging the exhaust. Guess uphill under power could produce the same effect."

In responce to this, how can I know for sure if it is the cat and if it is what are my options, do I need to replace it or is it fixable. I have not noticed I difference on acceleration however, just on the hills.

thanks a lot