1991 Acclaim extreme acceleration problems

My 1991 Plymouth Acclaim has been accelerating extremely poorly ever since I replaced the head gasket. I replaced the head gasket because it had cracked and pressure was leaking into the coolant. That problem is solved now. I have a new problem now though. When I try to accelerate the car moves extremely slowly no matter how hard I push on the pedal. I'll try to tell what happens in each of the gears.
All Gears: Acclerates decent right at the beggining, then barely accelerates in the middle of the gear, then toward the top end accelerates again.
Neutral: Engine revs up right with pedal, sounds great!
1st Gear: Slow acceleration, seems to respond to pedal alright
2nd Gear: Even slower, the pedal makes little difference in acceleration
3rd Gear: Stumbles a little bit when acclerating and pedal makes no difference unless I floor it and then it kicks into passing gear which is still slow.
4th Gear: Barely accelerates at all: Pedal still makes little difference in acceleration.

Like it says above the car is revs fine in neutral but when in drive doesn't seem to have much power at all.
I have the Haynes Manual and it says that it could be the Fuel Injection system, Incorrect Ignition timing, excessive play in distributor shaft, worn rotor distributor cap, spark wires, spark plugs, faulty coil, clutch slipping (no noise so probably not it), Emissions system not functioning (maybe PCV Valve), low or uneven cylinder compression pressures.
If you have any suggestions that would be helpful. Thanks for reading!

Double check your timing belt installation. One of the sprockets is off by a tooth.

Problem fixed. I just had to adjust the timing. Used a timing light. Works great now thanx for all the help. Runs better now than it used to! :wink: