Shaking and burning smell

Couple of days ago I start my car and it's shaking badly and doesn't have the amount of power. Like I have to go into higher rpm's to get up to speed, and if you idle for a minute or drive a bit you can smell something burning. I first checked plug wires making sure they were in good condition and not against anything hot, then I looked for foaming in the oil, then I looked for hoses that are worn, bubbled, kinked and I couldn't find anything. Checked my transmission fluid that was fine should also mention. It doesn't always do it when I start the car. Yesterday it was fine for a bit then it started again.