Have you tried taking a vacuum reading to see if you have a restricted exhaust system? If your cat gets plugged up it will be real low on power. I can't remeber exactly what your looking for the vacuum to be doing, but first off you should be between 17 and 22 i believe if your lower than 17 you may have a timing issue. Timing belts don't usually jump a tooth unless someone didn't install them correctly, but when they get worn out they do stretch and the timing advance gets all screwed up cuz there is too much slack in the belt. You should have your belt changed anyway if you haven't done it. To see if you have a clogged exhaust i think your looking for a continuous drop in vacuum if you hold the rpms up a little bit. If no problem there check fuel pressure.