99 sable Idoling strange chugging n jerking

My car recently started to run strange. It will not start without giving it gas. And wouldn't idol properly, check engine light would flash. I took it in and had the altinator and battery checked which were both ok. Found a vacuume hose that was disconnected and reconnected it and the car ran great for a few days. Then acted up once again. Had the engine light read and it said I had an air leak and a misfire I. Cylinder 1. I had a new fuel filter put in (severely plugged) an new wires and plugs. Found another disconnected vacuume line. The car now runs even worse. If it is cold it will not idol at all. The moment you remove your foot from the gas it dies. If it is warm it will idol around 500 rpm with the needle bouncing and car chugging and jerking. The engine light again is back on and flashing when the car is Idoling.