The engine is in the car but is not running correctly.

Its a 347 efi with msd digital 6 plus ignition.

The engine is sputtering and cutting out. It wants to die when you push the clutch to come to a stop. I notice when barely on the throttle it runs the best. When limping home in 5th at 40 to 50 mph? It does not sputter (much) but is not running correctly either.

When rolling down the road if i push in the clutch and rev it a little then engage the clutch it will accelerate for a moment then back to sputtering.

The car a been driven very little for the last four months, so i thought bad gas and added fuel from 1/4 to 3/4 of a tank. I cant say it helped, i drove it about 15 miles after adding fuel. Four months ago it ran good but still wanted to die when stopping.

My first thought is low fuel pressure?

Anybody have any thoughts or experience with these kind of symptoms?