Dodge Daytona Engine Runs Rough

I Just Rebuilt A 1995 Dodge Dakota Pickup With A 2.5 4 Cly Motor. It Did Very Good For About 300 Miles And Now The Oil Has Turned Jet Black...

Started Running Rough And When Pressing On The Gas Pedal A Lot Of Rattling Noise, But The Idle On Tach Is Steady At 1,000 In Idle.

Engine Problem 1989 Dodge Daytona 4 Cyl Two Wheel Drive Manual 70k Miles At Aprk 2200rpm After Warm It Runs Rough Like Missing Put In...