hello everyone

I have a 16 y.o. Volvo 740 GL (no lambda sensor) that had already made
180K miles (290K Km). it is a very sturdy and reliable car, not rusty.
engine is B200E, Constant Injection System.

the only problem I am having with it is that it is misfiring badly on
idle. driving range is fine, no power loss, no twitching on
acceleration. idle is really bad though, I suspect the engine at times
is running on two cylinders. when heating up after cold start
(additional injector in action), seems to run much more stable, but once
warmed up, starts to misfire. afaics, exhausts smell petrol.

I checked the ignition system and replaced most of it - it is not to
blame for sure. recently I replaced the cylinder head gasket and other
gaskets that go with this procedure. compression is fine, even a bit
higher than the manual says.

I suspect either injectors, or fuel distributor or insufficient vacuum
in the inlet manifold. I tried taking injectors out to check fuel
atomisation, the engine won't start. perhaps I should have plugged the
injector hole to keep vacuum ?

any ideas ? is it common for these injectors to get clogged ? I asked
local injector cleaning specialists and they told me that they don't
clean this type of injectors. maybe I can clean them myself with a
little acetone ?

thanks very much in advance guys. I really like this car and don't want
to drive it to the scrapyard yet because of such a stupid problem.

/max