740 Low Power, Low Speed had VERY low Power. Knock Sensor? Coil?
 

My 1991 Volvo 740 non turbo has little power. From 0 to 10 miles an hour takes what seems like forever, reguardless ifi floor it or try to coax it along. From then on it seems to 'catch' and run better, but not at all great.
The car's self diagnosis was a bad knock senser. I ordered one and changed it, and it didn't help. The manual speaks of 2 knock sensors. I can only find 1. Is there only one on some models.... or could they possible look different?
My dad thinks the problem might be a weak coil because the spark was orange/redish and not blue.
But the car itself said it was a knock sensor.... but a new one didn't help.

Any suggestions?
The spark plugs have been changed and gapped correctly, the plug wires are new, the fuel filter is new, the coil wire is new...