Engine missfire/shaking

My car all of a sudden started to shake really bad almost like it was about to stall. It doesn't turn off when stopped but it will constantly shake even if I accellerate. Also while driving the car seems like it doesn't have power. It will accelerate very slowly and when going uphill it slows down to about 35mph and only picks up speed once the hill is over. All started as I was making a family trip. I looked under the hood and found out that one end of the vacuum hose(PCV) was damaged so I replaced it. I replaced plugs, wires, fuel filter, air filter, PCV valve. Still no progress. I checked the engine mounts and they are ok. It doesn't seem like there is any air leak. All fluids are ok. I'm out of ideas. Is there anything I can check before having to pay someone to look at it? Thanks. Simone