Volvo Repair: fuel injector diagnossis, volvo 940, compression test

Question
i have a 1994 Volvo 940 turbo after a 30-60min drive when coming to an idle the vehicle will run rough, i have done the usual tune up, and have found that when the rough idle concern happens by removing one injector plug at a time i found the first injector doesn't change the concern rough running, when removing all the other injector plugs at a time, the vehicle wants to stall run worse, so is it the injector or possible the wiring harness?

Answer
Joseph, this sounds like an ect sensor issue.  It may be overfueling when it gets hot.  Did you replace the dist cap, rotor and wires?  What brand did you use?  Ive seen when junk parts are used other than bosch, crazy stuff happens.  I would do a compression test on cylinder 1 and 2 also. Roger