power surge whilst driving

hi all again

when driving the 1.8 petrol freelander 1999 at say a constant speed of 20mph and trying to hold it at that speed on flat road it feels as if the car is trying to stop and go, bit hard to explain really and it is not really noticeable but kind of like when your driving an old mini when its damp, not really noticed a misfire as such but just a slight hesistance on and off when holding at constant speeds,

any ideas?

gaz

leads, plugs, dizzy cap, throttle body, crankshaft sensor, fuel filter, fuel pump, the list goes on

it looks like replace and try till i find the problem then, is your list in order of most likely or is just better to try cheapest first and work upwards?

gaz

as an extra question, what effect would i expect if the cam belt timing was one tooth out on both cams?