Volvo Repair: Engine, coolant temperature sensor, engine coolant temperature sensor

Question
Car started doing this last Thursday June 17:
1.  When slowing down to stop, sometimes all the lights across the dash come on; sometimes it also stalls.
2.  Smells gassy at times; using a lot.
3.  Smells of exhaust at times.
4.  Spark plugs carboned; changed them; still does above 3.
1988 Volvo 240; app 144,000 miles
Have had it about 1-1/2 years; distributor and air mass meter replaced since we got it.  

Answer
sounds like it is running rich(too much fuel).there could be many reasons for this including the airmass meter.it could be the O2 sensor,throttle switch,engine coolant temperature sensor,fuel control unit,bad injector,or a wiring problem.it will need to be looked at for a proper diagnosis so the above mentioned items can be checked and each one eliminated as the source of the problem.sorry I could not help more.