You don't want to turn it off. Low engine power means there is something seriously wrong. You need to take it to a repair shop, find out what the problem is and they will turn it off as part of the fix.
Most likely crankshaft position sensor. The check engine light will eventually come on also. This exact thing happened to my cobalt. I drove it for 2 days before the check engine light came on. $30 fix.
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