Hi Guys, I've been working on a few ideas about what would be the cause of this problem. My '99 Discovery 4.0 has had an intermittent problem with stumbling and sometimes stalling but it only occured either at stops or starts. With this in mind and looking on this and other sites for possible fixes I replaced the stepper motor among other things.
Last week I took a quick 5hr trip to Ft.Lauderdale and noticed that along the way at appx. 75MPH it would loose power and stumble for about 10 seconds or so and then pick up speed again. This happened about 3 times during my return trip. When I got back I did a little more research and found that this particular pattern also occurs when the Vehicle Speed Sensor is going bad. Now before I go out and spend the $100 to have one sent to me I'd like the forums 2 cents on this fix.
Does this sound like a possible solution? Thanks for your input.
BTW this is what I've done so far:
New Magnacore 8mm plug wires
New plugs (Bosch Platinum) I know about the controversy here...
Cleaned PCV oil separator
New Stepper Motor
__________________
9dawgs 
'99 Discovery I
'99 Chevy Astro 4X2 w/4" Lift (family truckster)
17' Basstracker w/40HP Mercury
11' Jon Boat w/numerous antique outboards
