I have a 2001 firebird and sometimes when I start it the Check Engine Light blinks and it idles rough for about a min.
also it looses power sometimes I have put a new full pump on it but it didn't help !!
I replaced the  o2 sensor ,and it didn't fix it , someone told me it was the Mass air flow sensor. I was wondering how I could look at a picture of it, I was looking on E-Bay but I have no clue what it looks like.
 
                 Thanks for any help !!!  

I had that happen to me and it was the stupid air filter that I forgot to change after a log time.  

That sensor should be half way between the throttle body and the air filter.  So it is a round object that has electric wires attached to it.  

V6 or V8? I am not familiar with the V6 cars, but I do know that the MAF sensor is in the same location as the LS1. Look directly behind the intake lid. There should be an AIR sensor in the lid with a wire leading to that, the very next set of wires lead up to the MAF sensor, and should have a clip plug from the top.

Your problem could be a number of things, and listening to a mechanic may not be the best idea. If you went to a mechanic and he has had you replace multiple items on the car, I am willing to bet that you bought them through him. He may just be trying to pull a fast one on you, but who am I to say. I just feel an experienced mechanic wouldn't have you running around buying parts, he could identify your problem immediately, and know of a few ways to potentially fix your issue.

There could be a tuning related issue, and that could all be attributed to a dirty MAF sensor. If you are no mechanically inclined, I would suggest getting a professional to clean of the sensors, since they are very delicate.

You may also be dealing with leaking injectors. Injectors may stick open just a bit when the car gets hot, or if the car is cold, they may do it then too. I would look into that after you have identified that your MAF wasn't the issue.

Also, depending on the mileage of your car, it may be a good idea to change the fuel filter. If it has been clogged it will do exactly what you are talking about, and may make the car feel like it is dying, it will try to idle low, and it will have a delayed throttle (power loss). This usually means it's very clogged up in there, it's a good idea to change it out every 30,000 miles IMO. At $9.00 each, and ease of install, it's not a big issue.

Please keep us posted on your situation.

Thank
~Kevin  

As far as the check engine light goes, when you start your car it will always blink or light up to let you know that the bulb is working. If it blinks after the start-up procedure, and stays on you have thrown an engine code. You need to address the code, fix it, then delete the code.

There shouldn't be any connection with your check engine light, and you current problem. The engine computer wont be able to detect something as trivial as a leaking injector, dirty maf, dirty air filter, clogged fuel filter, or weakening fuel pump. It sucks, I know, but engine codes usually display something that needs quick attention. It will, however, detect failing o2 sensors, and show you exactly which one is problematic. If the light stays on, check the code, that will steer you in the right direction for your issue. Otherwise, it is more than likely one of the problems listed above.