20 Most Recent 2000 Ford Focus - Page 4 Questions & Answers

Instrument cluster maybe !

If your A/C compressor clutch is binding or seized, - the extra load will slow down the engine as everything runs on 1 belt on this car - check your Freon level and refill or replace the clutch/compressor

This is not a fuse issue, it is most likely a brake light switch problem, test that first with a 12 volt test light, there should be power in and out of the switch when the brake pedal is depressed. The switch of course is above the brake pedal arm which depresses it to operate the circuit.

Crankshaft Belt Pulley 85 ft.lb


Rear crankshaft oil seal carrier 15 ft.lb
Camshaft Timing Belt Pulleys 50 ft.lb

Camshaft timing belt pulleys 50 ft.lb

Same TIGHTENING Sequence for Single OHC

I read no place in the post that you have performed an OBD2 fault code test, you must do that test first, it is the key to fixing all electronically controlled engine issues like this

Rough Running Engine - James on Engines #2 - Bell Performance

https://www.bellperformance.com/blog/rough-running-engine

Apr 21, 2015 - When diagnosing an engine with a rough idle, there are certain things that must be ... If the problem does not reoccur, the codes will be erased by the computer. ... when accelerating the vehicle, which causes a higher fuel demand. .... it was water in gas...added added Gas LineAntifreeze/Water Remover.

Sounds like you might have damaged intake valves and worn piston rings.