It depends, did you use the proper chemical spray made specifically for MAF's? The sensor elements inside of those are extremely sensitive and can go haywire if you touch it or leave residue behind. I would double check for vacuum leaks first and if the problem persists clean it again to see if there is any improvement. I got a CEL some time ago and after cleaning my MAF thoroughly it went away.
When you unplug the MAF the ECU will calculate stock parameters on what the air flow should be and run fine. Basically you would be running speed density instead of mass air. Here is a good link I stumbled across awhile back on this site about troubleshooting MAF.
Yes it was only sputtering at low rpms. That is now gone. Installed a different MAF from another mustang that has no issues same thing. The only thing is I haven't had the new pigtail and a different MAF at the same time yet. It is almost feeling like a coil pack now. That would be a weird coincidence
Are you getting any CEL's? If a COP were to go bad on any one cylinder you would get a CEL. Also I have had COP's go bad and a sure sign for me when one went bad was at start up when I turn over the key the engine would clatter for a split second cause the COP was lacking spark in one of the cylinders. When was the last time you checked your plugs for a fouled tip or wet tip? Or when were they last changed or what kind of plug are you using? I would really like to know if you are getting any CEL's and if so what are they. How long has this been going on? Is this something new or old? It could be a case of bad fuel, or a clogged injector. Did you recently run the tank low before a fillup? Sometimes debris from the tank will clog an injector too.
New fuel filter two weeks ago also. Using Bosch platinum +4. Has has small hesitation almost loading up at low rpm under 2k. So I replaced fuel filter and plugs and ran sea foam thru tank. Had 3:55 installed and the day I brought it home I removed MAF to clean put back in and low rpm he's rotation cleared but now bad miss and black smoke at 3/4 or more throttle. No lights nothing. Put MAF from another car in no change. Put a new pigtail on and it's better but not right. Maybe I somehow messed plug up at the same time as the MAF went bad. I haven't yet had the new pigtail and a different MAF on at the same time will try that today.
Seafoam would cause the black smoke as it may still be in your tank and cleaning still. The injector(s) may be clogged due to the seafoam. I have seen that and done that myself before. I the MAF was just a coinsedence though. I would look toward a partially blocked injector or those Bosch plugs. That last part was my opinion coming into play, I hate Bosch. I think they are the worst for our application.
man, do yourself a favor and get a boost gauge, and a wideband afr gauge. That's the only way you will know what's going on with your car on a regular basis