Peugeot 505 Sri A Injection Drowns

I have a Peugeot 505 SRI with electronic fuel injection that stalls when the car is moving. The strange thing is that when the car is stationary, I don't have this problem. I hope you can help me.
Hector 63

You have a cracked fuel line; it's leaking air and the engine stalls. When it's not running, it doesn't stall because the engine isn't revving. Try pressing the accelerator while the engine is moving. Cheers.

Robertv

Thanks for your reply, but it's still not working. This Peugeot model came with a Renault 2.2 fuel-injected engine (gasoline), and it has a mass airflow sensor. The engine starts normally on gasoline and doesn't stall (idle), but it stalls when I accelerate. What I find strange is that it runs perfectly fine on CNG (compressed natural gas). Thanks again, looking forward to your reply.
Hector 63