Engine hunting

Hi peeps,

I've got a small engine problem that someone out there may have an answer to; when the engine revs level out after accelerating or de-celerating rather than continue cruising smoothly at level revs they dip at half second (ish) intervals by about 400 revs for about 2 seconds then level out. Any ideas?

Also, my leaky targa roofs are really starting to p*** me off severely as they leak both on passenger side and drivers, right on my leg when I'm driving. Any ideas how I can stop it?

Any thoughts on either of the above will, as always, be massively appreciated. Ta.:confused: