My 1986 944 that has had a perfect smooth idle at 900 for ages has recently started
to misfire on idle. I have replaced plugs
and inspected distributor and injectors but
I can't locate the fault.
Seems to run fine under power but pops,
bangs and runs rough under 2000.

What should I be looking for?

 

Found the problem at last.

Air leak on inlet manifold gasket.
Geez, why didn't I check that first!
£1.63 for new gasket and 15 minutes
to fit. Now purring as normal...

Dave