1999 Toyota Camry hard to gas pedal, a smell from the car h

About 3 years ago we had our o2 sensor replaced the car has California emissions. This year the engine light came back on with the same code O2 sensor, failed a inspection but replaced the thermostat. The engine light went off. Now and then every once in a while the car was hard to start from since when we got it in 2005.
But now the car is doing it more often but now there is a funny smell the car gives off and the car is consuming a lot of oil. The gas pedal is always hard to push every once and while. Can someone help me to avoid a big Toyota bill?