My car has been stumbling when I am idling for quite some time now. For some reason I really think it is the mass air flow sensor. Here is what I checked or replaced, IAC, fuel filter, plugs and wires, EGR, TPS and checked for vacuum leaks.
I tap the maf and the idle doesn't chance. When I unplug it, the car stalls. It will start back up and run though with it unplugged. Does this mean it is bad? Is there any other ways I could check?
Thanks

 

Doesnt sound like its bad to me.

Find a dark spot at night, open the hood... and look for a light show. Sounds to me like a misfire/ignition issue.

 

Well today I unplugged the maf sensor while the car was running. It stalled. I started it up and drove it around without it plugged in all day today. The idle only moved a tiny bit up and down and sounded like its "cammin", but not as bad as it did before. I could definately notice a difference. I also let it idle for over 45 minutes and it never stalled. Whenever I would come up to a stop light the idle would start stumbling and sometimes it would jump real high and stall.
Do I have to take my air snorkel out to look in the mass air flow sensor for the glow?

 

Try starting the car and let it get to closed loop, with it idling gently rap on the sensor housing with a screwdriver handle and see if the engine reacts to that by either dying or running better. If either happens then your MAF is bad.

 

Whats the story on the engine? Stock?
Sounds to me like you need to check the TPS and IAC settings. I would also disconnect the fuse for the ECM for a minute and see how it runs after that. The fuse is on the radiator support, battery side.

 

As mentioned, I have tried that earlier and nothing happened.

 

The engine is a L98 355 with keith black pistons, 3 angle valve job and a compucam cam. It's supposedly close to the stock size though. It's also got a Lingenfelter mr gasket ecu chip. When I first bought the car it did this slightly and you could barely notice. Now its kind of bad sometimes.

Oh yeah, I have a scanner that can get readings from the maf, but I am not sure what they are supposed to be at when it is at idle.

After I unplugged the maf I just scanned the codes and I get 13-Oxygen sensor(which is brand new and heated) 33 and 36

 

Does it do it all the time, or only when the engine is cold or on cold days?

 

When you first start it up it isn't bad. After a few minutes it does it in all weather cold or hot.

 

MAF should be around 9 gms at idle but anything up to about 20 is ok...if it is less than 9 gms at idle double check the minimum air setting followed by TPS.

I would also suspect the aftermarket chip.

 

More than likely its the MAF settings in the chip, its not set up right for your combo. You can try a lower TPS setting and it will help, but the chip needs reprogramming.

 

When I put my scanner on the maf readings I think it says 7 at idle

 

If you have the dreaded 33 error code, the ECM will be in limp home mode. Not very fun to drive a 3rd gen MAF car with the 33 error code.

Disconnect the negative battery terminal and wait 3 minutes and then reconnect. This will reset the ECM (remove all error codes).

Start the engine and let the ECM go into closed loop mode while idleing, then do the MAF tapping test. Then take the car out for a short drive and get back to us.

Apparently, if the MAF passed the tapping test, then the MAF is OK. BUT, this test should be conducted w/o the ECM being in limp home mode, and when the ECM is in closed loop, as stated above.

 

I cleared all the codes and they haven't come back. I tried the tapping test a number of times. What I was told by the previous owner is that it gives bad readings, but it still works. So how do I know if it is giving bad readings?

 

Because you have the 33 error code, you might be confusing 'limp home mode' with bad readings from the MAF sensor. Limp home mode is very fustrating and the car has no power and runs erratic.

Once your clear the codes, how does the car run?
Is it back to normal?

 

Buy a scanner for around $30 . Check your codes. Simple. and saves money in the long run.

 

Paperclip is "free" and works as good or better than a code scanner.

 

Like I mentioned in my post. I do have a scanner that I can check all the readings from the computer. It is an OTC system.

 

The codes didn't come on until I unplugged it and plugged it back in. I reset them and they haven't come back on. It still idles the same though.