Volvo Repair: B243F poor economy, pressure result, fault trace

Question
dear Regis ,
   I have 940GLT 1992 with B234F engine 16valve ... It consumes too much fuel and its idle roughly with not stable revolutions ( keep varying between 650 - 850 ) rapidly ... I didn't leave anything to check ... starting from vacum leak to the end .. and changed the injectors and the air mass ..etc ... manythings .... at the end I just have to things to suspect ... iether there is something wrong in the head , or the ECU faulty ... I checked the pressure and the read was 11,9 for all cylenders , is this reading high or good ? if its high why it could be ? and can the pressure result be like this and the head is faulty ? and how can I test the ECU ? and what is the part number for the origional ECU for this car ? maybe the previous owner change it with not compatible one
WITH MY REGARDS  

Answer
this reading is ok.there is no way to test the ECU.part numbers change over the years the one in it may not match a new part number it would have to be checked by the old number and see if this number changes to the new part number.this car will need to be looked at and each sensor tested to fault trace this problem