Focus MK1 2.0 gets up to 3000 revs but then dies off

[pstampy]

Hi guys, really appreciate any ideas on this one.
Recently got hold of an old MK1 Focus for a runaround, and have been trying to sort out all of the niggly problems. A big one has reared its head though.
Had this on Wednesday and again tonight - just managed to get the car up the M3 after more than a couple of stops on the hard shoulder!
Car revs fine when its idle, but when you are driving you can go through 1st and second gear, accelerating, perfectly fine, but when you get to about 3000 revs (3rd/4th) the car begins to lose power and eventually drop to about 20mph before it will pick up again. Putting your foot to the floor does nothing, and it runs a bit rough.
I've changed spark plugs and ignition leads, battery was changed recently too. Car starts fine. Ignition leads "seem" to have stopped another problem, which was the car sometimes stalling or the battery light coming on/revs dropping too low when you fully depress the clutch or pull up at a junction or roundabout.
One issue I know of is an oil leak from the rocker cover, gasket changed but cover is warped and will need to be replaced. Don't think these are connected?

[MC Bodge]

MAF, Lambda sensor?

[Munter]

The speedo's not failing at the same time is it? Just you mention stalling problems. And mine would stall when clutch depressed and the speedo failed. The speed sensor in the gearbox was the cure for that.

[pstampy]

Speedo seems okay, i've ordered a new coil pack (last roll of the dice) so if that doesn't work loks like it will need a diagnostic check.

[Zad]

Coil pack would have been my guess too. It sounds like it is getting to a certain temperature and then going open circuit.

[Pumaracing]

No it isn't the coil pack. Most likely the fuel filter is blocked.

[Pushrod-Power]

Get the fuel pressure checked preferably when fault exists,then take things from here.