Yes if the timing belt is off one notch at the crank, the engine will be very down on power.

I would check both the belt installation and the ignition timing as suggested.

For the belt check, remove the fan; remove the fan shroud, and then the timing belt cover. I don't remember if you must remove the small bolts from the front of the crank pulley to see the timing mark.

Crank the engine by hand with a wrench on the crank till the timing marks line up. Do this in the clockwise or normal engine running direction only. Ignore the stripes on the belt at this time. Make sure the crank pulley notch is at 11 o'clock. Loosen and then retighten tensioner bolt.

Now remove the oil filler cap a check that the cam lobes for #1 are both pointing up in a V, both vales closed.

Now remove the distributor cap and check that the rotor is pointing directly at plug wire #1.

If all ok, reassemble, start engine and check ignition timing.

If all ok, reassemble, start engine and check ignition timming.