I have an Australia-built Ford Falcon which has a 4.0L multi-point fuel injected straight 6 and is manual. I rebuilt the head in the car myself last year (blown head gasket) and it has been running fine since.
It’s always had a funny slight flat spot under acceleration. Around 2,500 RPM it struggles to move past until I accelerate harder, then it kind of jumps up to where it should be. Semi-violently.
This more recent problem is that it will stall while driving. I can be doing any speed and be at any point into the journey (10 minutes or an hour, it doesn’t matter) and it will just die. Typically the RPM will just drop to 0, the battery light comes on, and I will just be coasting along along in gear. Knowing that it’s turning over, I usually plant my foot, and it all of a sudden will roar back to life after no specific period of time. This morning it was a good couple of seconds (I was doing about 80 km/h, and it kicked back in when I had slowed to about 60 km/h). Other times it dies and then comes back in almost straight away.
It also can die while stationary at traffic lights etc, it will usually start back up but again today it just turned over and over and over and didn't start for about 30 seconds.
I’m thinking it could be:
- Fuel pump
- Coil / Dizzy
- Some kind of air / exhaust sensor
The problem is because it’s so intermittent and hard to replicate, I don't know how to diagnose it better myself and don’t know where to start.