When driving, pressing on gas to accelerate car acts like it has no power. If I press pedal hard almost or to the floor it will go but with very little power. Has very hard time going up hills. It happened a couple weeks ago the first time, went away, and came back. I took it to Auto Zone to read the code for 'check engine soon' light. Codes came up camshaft senfor and mass air flow sensor. Replaced camshaft sensor and cleaned MAF with cleaner. Check engine light is now off and was ok for a day or two but problem is back. When accelerating from a stop car will rev up hard to about 25mph and then go very slow. Can go on highway and get up to about 70/75mph tops. If i try to accelerate sometime car seems to jerk or shake slightly.