No revs at all in any other gear including neutral?

Thanks Ken L, can't try your suggestions until the weekend because of work, but still don't understand why throttle works perfectly in "Park" but no other gear position! Also, after disconnecting neg lead on battery car/spanner light goes out and all gears/revs all work ok for about 6 minutes, the light comes on back to no revs, this is not "limp mode" as the car is only creeping in its gear, any resistance/incline no movement, so would never get you home or to garage!

Thanks Ken, I'm old school (points, rotor arm, condenser, distributor cap, etc, ) I'll have to buy a code reader tomorrow I suppose for this computer stuff, although AA man plugged his in at the scene, and it said no faults! And just so there's no misunderstanding it is the car with spanner light that comes on, that stops revs not engine management light!
Dave

Hi Ken, got scanner and plugged in not much help, shows connection profile to car screen changes and says 2 faults detected, screen changes automatically after a few seconds, with read codes, erase codes etc, but when I press read codes it says "no fault codes stored in module" I tried it several times, also scanner lists monitors as all being N/A not sure what that means! On the practical side I've checked all wiring connections/plugs on sensors etc, no obvious damage /dirt/ corrosion, nothing changes, starts up in the morning runs beautifully, no car and spanner light on, can drive around as normal 30 /40 mph all gears changing normally for about 7 mins (between 6 and 10 minutes) then car and spanner light comes on and no revs accept if gear lever is in park position, also noted that to move lever out of park must put foot on brake pedal, (standard auto safety measure)but if I press brake pedal and leave gear lever in "park" it will not rev when I press the accelerator pedal unless I release brake pedal then revs normally. Any ideas, guesses, answers would be appreciated. Now torrential rain has stopped and I'm not working till the weeekend I'm going to strip down the throttle components as per your first suggestions.
Dave

No good stripped down and cleaned throttle body, with some carburetor cleaner it wasn't particularly dirty, but now its shiny clean in and out, reassembled, tightened up disconnected battery as scanner won't read or clear any faults. Left overnight started up this morning same thing run drives perfectly for 7 minutes then no revs, borrowed a working throttle pedal unit and connected up just to eliminate, exactly the same still no difference.