My 316i se is heavy on petrol any ideas y - 1999 BMW 323 Series

I would look into your fuel relay. This is a symptom of it going out. If I am reading this right. As you are driving your vehicle all of the sudden stops and you have to coast to a stop. It then takes some time to get it to start again but turning over fine. If this is the case then what I said should be it.

Black exhaust smoke can be caused by one or more leaky fuel injectors, too much fuel pressure (sticking fuel pressure regulator), a faulty MAF sensor or Oxygen sensor, or a engine computer fault.. You need a diagnostic test ran on the vehicle. Plug a scan tool into the OBD diagnostic connector and look for any fuel or sensor related fault codes. Test the fuel pressure and the fuel pressure regulator to see if they are operating within specifications. If normal, the next step is to figure out which injector(s) are leaking. You can remove the spark plugs and look for ones that are carbon fouled. Also inspect the air filter

Check compression and timing. Then check sensors(MAF, oil pressure sensor). Don't crank engine too long. Cranking engine may pour a lot of petrol into your engine oil.

Right behind the air filter. That is, toward the cabin from the air filter.
There is a air tube about 3" in diameter that runs from the air filter to the throttle right side of the engine as you face the front of the car. The MAF sensor will be a part of that tube.

bmw 316i se blower not working ,where is the fsr located any help would be helpful thanks

most likely the sender in the gas tank is bad.

That sounds like the petrol pickup pipe in the tank has an air leak and when the fuel is dropping down below the leak it is sucking in more air than petrol.
The most likely cause of that is either the gauge sender untit or the fuel pump itself leaking (if the fuel pump on that car is inside the tank).

Fit a new needle and seat assy. Check float is not heavy from absorbed petrol (porous).
Check fuel / float level is correct.
Check operation of automatic choke .

try un pluging your map sencer if your motor run better then the sencer was bad. give that a try good luck.

bmw only make manual for the common car and not for a model