My father in law gave me his 08 5spd vibe a couple months ago and I'm loving this thing! Had to press in a front right wheel bearing but other than that the car is almost perfect. 115k on the clock and I'm hoping to see that number get much bigger. Looking forward to getting to know this community! :D

Hang on.... p0171 is a lean code. Is this code still pending in your ECM? CEL on?

Ahhhh between the cat and the res you could go cheap and buy an exhaust sleeve off Amazon. I've done this with my old subaru. They are like $10. You probably need new exhaust hangers as well.

Loss of compression after over heating.... May need a new head gasket if the head is now warped. You would also need to have the old head machined to make it flat again. This is an expensive problem if your not going to fix it yourself. A used motor can be a roll of the dice. Could have oil consumpt...

Ooooo check the studs for signs of stretching. Maybe the lug nuts have been torqued too tight. I'd check all of them around the car.

Have you looked underneath the car yet? Put eyes on it. Maybe the cv boot is open.

Jack it up and shake down the front end any play.

Look for grease around the cv boots.