rough idle mystery

i have a 1981 vw rabbit pickup with a 1.7 gas motor. bought
it a few months ago from a guu who had it sitting in his
barn for the padt 6 years. it wasnt running when i bought
but after many weekends i finnally got it running. my
problem now is it was a rough idle where it appears
cylinders 1 and 4 are misfiring maybe. ive replaced spark
plugs, fuel filter, cap, rotor, plug wires air filter, injector seals
ect. the works. it drives great but idle is very rough. i
decided to take it to a shop to have a proffesional loom into
the deal and this is what he did: repaired vacuum leaks,
balve adjustment, checked timing and everything checked
out good. he did a compression test, the results were: cyl.
1: 170 2:150 3:150 4:170 and a leak down test and the
results were cyl. 1: 0-40% 2: 20% 3: 30% 4: 10-50%.  so
basically the two cylinders with the best compression had
the worst leak down. and those are the cylinders that
appear to miss at idle. the strangest part is when you pull
the wire on either 1 or 4 the idle smooths out and idle
increases where if you pull 2 or 3 idle drops like its
supposed too. what would cause idle to increase and
engine to smooth out when you disconnect th cylinder? and
yes the firing order is correct. the mechanic i took it to said
he didnt know ehat would cause that, the only thing he
could think of would it might need a valve job but couldnt
tell me for sure. any ideas??