power lag/loss problem
 

I'm looking for some technical advice on my occasional power loss/lag problem in my 1983 944.

Sometimes, and only sometimes, before the engine gets warmed up there is a serious problem for the car to accelerate. It feels as though not enough fuel is not getting delievered. When I go to full throttle, the symptoms go away. Otherwise the car seriously lags for a few seconds, or sputters until something sounds like it catches and the car takes off. After minimal warm up, this ever happens again.

Any ideas on what could be wrong?

I've also noticed some diminished MPG recently, but I'm not sure if it's related.