I am having trouble driving my '65 Beetle at low speeds. The ratios are standard and so are fairly low (1st only does to about 10mph, 2nd to around 20, 3rd up to 40 and 4th up to 80) however when slowing down to say 15 to 20mph for speed bumps etc.. I will get a juttering sensation as if the car was losing and gaining power extremely quickly. As well as this I also have an issue with the car revving exceptionally high (No rev counter so not sure specifically) when idling or on tick over. Does anybody else have any similar issues or any methods to remedy this?

Many thanks in advance :)

tl;dr: Stuttering at low speeds, OTT high revs on tick-over and idling. Remedies or Fixes?