Volvo Repair: volvo problem, volvo 240, proper diagnosis

Question
hi regis i hope you can help me with this problem i have a 1990 volvo 240 my car just wont run it shakes awful and wont accelerate at all i have tested all vac hoses, all injectors, replaced both fuel pumps had air mass meter tested it tested ok but it seems to be getting either too much fuel or not enough the plugs are either white or the next time i check them they are all black also i had the timing checked do you have any ideas  thanks papa j

Answer
there are really many things that can cause this type problem.it will need to be loked at for a proper diagnosis.each sesnor will need to be checked when there is a problem also it could be hooked to a scan tool to monitor each sensor and see which one may have a faulty signal.