Mk2 with jumpy acceleration

I would be grateful for any advice.  My 2000 Mk2 1.8 has been running very well, but recently it developed a problem when accelerating.  I thought it might just be due to the cold and wet and not having been run for a couple of weeks, but I have given the car several long runs and it hasn’t sorted itself out.  The car starts ok, and will cruise along at 70mph (or hold any speed) without a problem, but when accelerating it is very jumpy. It idles ok.  Many thanks for any tips. 

The plug leads are probably 10 years old now, lead failure is a common cause of the symptoms you describe

 Many thanks for your advice Geoff, I have just ordered a new set of leads.  David

Albeit a post from while ago, worked a treat for me, changed all leads and also gave the MAF a clean with electrical cleaner. Runs a dream again :+1:t3::+1:t3: