I just bought an '86 Samurai a few months back with what I thought was carburetor problems.  The guy said it had a rebuild Weber on it, but the rebuild was never right.  The idle was racing, performance was sluggish on takeoff until past about 2000 RPM but seemed to smooth out at higher RPM.  I put a brand new Weber 32/36 DGEV carb on it, and it seemed to work like a champ until a few days ago.  Now the thing has the idle racing again.  It also doesn't do it every time I come to a stop and push the clutch in...seems to be worse if I've just gone up a good hill and had to rev it a little higher.  Also seems worse when it's hotter outside.  Some things I've read say it may be the timing or vacuum leaks, but I wonder why it has been running fine and then it is doing this all of a sudden.  Any ideas???