1999 vw passat will start but will not stay started. Cuts off when accelerator released. Will not idle. Fuel and air filters replaced.

be checking emissions controls for vacuum leaks especially with the brakes..

With that many problems you should have gotten some error codes generated by your computer. Have you had your error codes read, so that you know where to start? While error codes usually won't take you to the exact problem they do put you in the general area of the problem.

When you replaced the fuel pump did you have good fuel pressure? Or did you not check it? While it does sound like a fuel problem, it could be in the spark system also. So the error codes are important to narrow it down.

it hard to say there few things that could cause this but sounds like it a Fuel issue
Possible bad fuel pump totallly clogged fuel filter bad injectors Out of gas etc.
first thing you need to do is check your fuel pressure ( I bet it be low ) if it low check fuel filter if fuel filter good replace fuel pump
If Fuel pressure is within Specs then test the injectors
if Fuel pressure is ok and injectors test out ok then check ignition system (spark plugs, coils, module etc)

Try cleaning throttle body with throttle body cleaner. Sometimes deposits build up and choke off air at the butterfly valve.

change the coil pack ,both of them if it has two on plug caps

have u tried changing the nleads

replace your fuel filter first. If that does not do it, then try an air-flow meter. (if the check engine light is on it may be an airflow meter.

change air filter.and fuel filter. replace plugs and wires.check tires air pressure.

it may need a tps {throttle positon sensor} switch.or the idle air control maybe gummed up or inopertive! this is just a guess!

you need a new fuel pump