1994 Chevy Cavalier Engine Vibrates badly after warm up

Engine starts great and idles for a few minutes just fine. Then after I cruise down the road ussually 5-20 minutes later and come to a complete stop the car will suddenly loose alot of power and start vibrating when accelerating. Then you can smell alot of unburnt gas from the exhaust. The engine surges in and out from running properly as im cruising down the road, sometimes it will run properly for an entire 60 minute drive, othertimes it will start bogging down minutes after start up.
To date I've changed: Spark plugs, Wires, Coil Packs, Fuel Filter and have used Fuel injector cleaner (Pour in gas tank stuff) Checked for codes, None came up.