The previous owner was up front and told me that a misfire had developed recently. I am fairly experienced motorcycle and diesel mechanic and was confident that I could fix it easily, but this has been a complete surprise. I won't complain too much, I only paid $2900 for the car and it has only 80k miles.

 

I've lost count how many vehicles I've had in the last 50 odd years and every one of them needed something doing to it, even the very rare new ones. It seems that the faults now are still there just harder to find. You may have seen the post on this forum.

Serious Misfire/Rough idle - No Codes showing. HELP!

If not there's some interesting reading there.
Keep at it mate, you'll find it eventually.