if the car hass been running fina,and last time i saw it when it was 3 ft behind my bumper at 80 mph she was running a bit too well.
and at slow speed it just stopped,if the belt is still on and the mecancial side is fine,and she has compression its fuel or spark.
compression would go over time,and a snapped belt you would hear.
very common cause.
earth strap engine to bodywork.battery terminals.battery earth.
fuse to fuel pump,or fuel pump.also check the pipes to the engine fuel lines.
turn key so the dash lights are on and if you can hear the engine componants moving
then turn engine over for around 20 turns,then remove a plug if its wet you have fuel.
so then check the wires that go into the plugs we had one come out of a map sensor that was fun.
check cam sensor,and crank sensor.
or if your in the aa or rac get them out.with this dam cars if you can plug them in in seconds you can see the problem.
the speed bump may be a red herring.
i dont think you can flood a injection system.it will be a basic fault if your car was running perfect before it broke down.
and also check the plug under the manifold .the issue is nowday the wires are getting old and sometimes they break away from the
plug,so give the wire a very gentle tug to make sure they are still connected.I also found swearing at the cars often does help.