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Was your foot off the throttle the entire time the car was stopped and is the engine warmed up? I have to ask but I am assuming the answer is yes.
Assuming the answer to the above is yes I'll point out first that 700 RPM is a steady engine speed sitting at a stop light with the engine idling. Now for possible causes:
If the engine isn't warmed up (even when it's 100 outside the engine still needs a little time to warm up) you could be seeing the transition from "choke" open loop mode to normal closed loop idle.
Inconsistently gapped spark plugs. They should be gapped between 0.028 and 0.032". If you're tuned the gap should be 0.026 and 0.028". Take a look at http://www.cruzetalk.com/forum/129-engine-transmission/6722-diy-re-gap-factory-spark-plugs.html for information on how to check and regap them.
If this doesn't fix the idle I would suspect a fouled injector or vacuum leak. For the fouled injector run a can of BG-40 fuel system cleaner through your tank. Run your tank to the low fuel warning light and then fill up with Shell vPower Premium and put the fuel system cleaner in the gas tank. A single bad tank of gas is all it takes to foul the fuel system.
Depending on when your car was made you could have the old style PCV valve/crankshaft cover, which is known problem and has been redesigned. This part is covered under the 5 yr/100,000 mile power train warranty and when it fails the car will throw a code.
Assuming the answer to the above is yes I'll point out first that 700 RPM is a steady engine speed sitting at a stop light with the engine idling. Now for possible causes:
If the engine isn't warmed up (even when it's 100 outside the engine still needs a little time to warm up) you could be seeing the transition from "choke" open loop mode to normal closed loop idle.
Inconsistently gapped spark plugs. They should be gapped between 0.028 and 0.032". If you're tuned the gap should be 0.026 and 0.028". Take a look at http://www.cruzetalk.com/forum/129-engine-transmission/6722-diy-re-gap-factory-spark-plugs.html for information on how to check and regap them.
If this doesn't fix the idle I would suspect a fouled injector or vacuum leak. For the fouled injector run a can of BG-40 fuel system cleaner through your tank. Run your tank to the low fuel warning light and then fill up with Shell vPower Premium and put the fuel system cleaner in the gas tank. A single bad tank of gas is all it takes to foul the fuel system.
Depending on when your car was made you could have the old style PCV valve/crankshaft cover, which is known problem and has been redesigned. This part is covered under the 5 yr/100,000 mile power train warranty and when it fails the car will throw a code.