Iv had a Mk1 1.8 Zetec petrol from new the faults iv had have been varied but nothing costing the earth .
1) Exhaust system a pain and most money spent. every part of it except Cat
2) Central Locking a real nightmare if it starts playing up .
3)Brake flexi pipes front and main brake lines
4) HANDBRAKE always been a pain cables stretch over time also snap and rear drum/s stick/ seize / squeal.
6)Drop Links on rear and front
7) Springs snapping also not sitting in cup correctly at end point.
8) PCV system hoses collapse or split.and valve itself sticks open/shut
9) Battery's chews them up and spits them out
10) Rear crankseal leaks due to PCV valve adding pressure to crankcase.
11) PUT THE CORRECT OIL IN 5W.30 FULLY SYNTHETIC NOTHING ELSE ZETECS DONT LIKE ANYTHING ELSE.
12) Clutch pedal position sensor top of pedal box. Cheap as chips.
If I think of more will post .