96 Jetta Power loss

The jetta is not a very powerful car to begin with but i seem to have lost some power. Before my dad and I changed the spark plugs and brakes it seemed to run alright and i could merge at a good speed. Now when i merge the most i can get up to before going downhill is 60 when the limit is 65 which isnt exactly safe. Anyone know why I may have a power loss and what i could do to fix it. I was thinking it may be spark plugs and maybe one isnt firing correctly or something.

Are your brakes rubbing? Did you check to see what the correct gap is when installing your plugs? And are they the right plugs for your car?

I do have it to the correct distance but I dont know if it is anything different for platinum spark plugs from bosch. Anyone have any insight on this? I just read my big service manual and i think I may need to do timing.

The Bosch platinum plugs are already properly gapped for the vehicle. How are the other maintenance items, particularly filters.

I recently tested my pedal to see how far it was opening and found it to be opening the throttle only 1/4 of the way. I believe the pedal is broken but as a temporary fix I took off the plastic governor under the pedal and now it opens the full way and the car flies now.

There is an adjustment clip that holds the cable position for proper tension. It's near the throttle valve on the top of the engine.

there could be air in the lines, bleed brakes, check for a leak where air might be getting in , also,when at a stop, does the brake pedal fade away, if so your master cylinder is bad, and a new one is like $70 and is easy to put on,(dont let a shop put it on, they want 360 for the part and 200 in labor when i did it in about 30 minutes)