I've got this progressively worse problem over the last few days. The car will have difficulty accelerating while still under 2200 RPMs. I don't have the misfire while revving the engine in park or reverse. Any thoughts?

 

Have you taken a look at your plugs? How old are the wires, cap, and rotor?

 

its more common for the engine to misfire under load, thats why it is not misfiring when you just rev it, try accelerating up a hill or things like that and it likely will, its probably yous plugs or rotor or dist. cap, you should just replace them all its cheap and easy, ipd makes a good replacement set of wires.