1991 Chevy Cavalier 91 cavalier loss of power and barely m

im looking for some direction to trouble shoot the issue i am having, its a 91 cavalier , car starts up fine and idles perfect but when you put it in drive and give it alittle gas it starts falling on its face with no power and struggle to get to 20mph. when you try to go up a hill you have to put it down in first and put it to the floor and it barely make sit up and still not going above 20 mph. last night i changed the fuel filter and also put new ingnition coils on and check the wires and plugs on the car. Anyone ever experience this before? any help or suggestions are apprecited thanks