Choking and jumping at 60mph

[V1NNY]

I'm driving along a t a steady 60mph for a while so the engine is at a good running temperature. On a very slight incline the engine starts to 'stutter' and feels like the car is choking, the engine malfunction lihgts and the locking lights flicker like mad and the rev counter goes daft.
When I pull over and leave it idling for a while (or turn the car off alltogether) it stops and I can continue on my journey.
Any suggestions to what this can be?
I've changed the spark plugs as I thought it may be a bad connection or something but it still 'jumps and coughs' when the lights go mad.
It's driving me bonkers and I really need some advice on this.

[lumpylarry]

possibly a bad coil coil or spark plug boot arcing when under load..
are you able to pull any trouble codes from the computer?

[V1NNY]

Thanks for such a quick response!
Where can I stick the wires to get the flash codes? I'm pretty green when it comes to cars and where to find things but I did get a guy to put it on diagnostics but he couldn't find anything/nothing came up. A guy in a motor factors said it could possibly be the spark pack. I know when I changed the spark plugs, one in particular was very 'burned' looking and I couldnt get it changed when I did the rest of them. Could this be the 'arcing' problem?
I'll spend a bit of time on it this weekend and see if it cures the problem.
Thanks