Hello - having issues with 1996 Discovery 4.0. Running rough so I tuned it up and had codes removed. Ran O.K., but after 2 days it started again - cuts in and out (miss firing) with rpm;s going up and down - then check engine light. Mechanic states that cylinder # 7 seems to be msiing every so often... Thinking maybe coil pack is going out or TPS Sensor. Any ideas?

Lastly, fuel filter replaced, but not fuel pump... do these go in and out or do they just go bad.

Thanks

crank sensor's common to fail and also, I have seen problems with these valve guides swelling/galling and causing the valves to stick and cause mis-fires; this is especially common on older Disco's and Rovers and seems to manifest more often after trips of more than an hour or so.
Of course, don't overlook the obvious.....plug wires.