I've lost lots of horsepower in the last year from an unknown reason. I did all the regular check-ups: changed spark plugs and wires, replaced air and fuel filter, engine is fine except for the catalytic converter. Can this cause a major loss in horsepower? The mechanic metioned something about problems with the fuel injectors maybe giving off to much or too less fuel at moments. What can be the cause of this?

 

YES!!!

How well would you perform if given a coffee straw and told to breathe through it as you ran the 10K?

You're asking the motor to do the same thing.

Some other gotcha's I've learned on this car...

Performance suffers at engine temps above 180... USE THE PROPER THERMOSTAT. the correct one is twice the depth of a normal one. If the wrong one is in the car it will overheat fast with the AC on, and overheat in general traffic in temps above 75 degrees. when the correct thermostat opened, it blocks off a port in the waterpump and coolant flows differently through the motor...

On the right side of the engine, the PCM (part of the ignition system) is bolted to the head of the motor. This $70 part fails before the OptiSpark because of the heat it endures... If you loose ignition or the car starts running like it jumpped time, replace this first. save yourself a $700 repair. I did my OptiSpark myself (it's not fun) only to find I still had no ignition.

Once the window motors go, get the lifetime motors, you will replace them more and more frequently.

Parts are hard to come by... Take care of it...

 

Oh yea, about the injectors...

Not likely. A blockage is not intermitent, and the computer controlls the opening and closing of the injectors...

I learned this when I looked into smaller injectors to save fuel... Unless I got a custom program on the chip, the computer would just keep the smaller injectors open longer.
larger ones would would be closed quicker. Ergo, no effect on economy / performance.