running crap sometimes

[highlander112001]

hi
starting to have an annoying problem with the old girl now
she a 325i s/2 ( does that mean tech 2 sport ) s.a. import
you can be driving along and suddenly its like it starts to miss fire then a few mins later it picks up and runs fine again does it all through the gear range and through rev range but gets worse around the 5.5k 6k rpm
so far I have changed the rotor arm , dizzy cap , all leads + spark plugs fuel filter in engine bay and new fuel pump = no change run out of ideas now

[highlander112001]

just a missfire sounds like its runnin on 5 then clears n runs fine