I've got a problem with my car stalling out. What else could it be?

It runs fine a majority of the time, but sometimes when I hit the gas it won't rev beyond like 2k RPM and isn't steady, the needle bounces between 1-2 even at full throttle. In order to fix it, I usually have to put it in neutral and restart the vehicle. Sounds electrical? I took it to a diagnostics, and they told me the throttle positioning sensor was bad, so I replaced that. It didn't fix the problem but it got rid of my check engine light. I then went ahead and put a straight pipe in instead of my catalaytic converter because that was the shops first guess before they ran a diagnostics. I then did a little research and found out that the m airflow sensor could be going bad, so I unplugged it and it seemed to help a little but it still did the stalling out thing. Given that I have no check engine lights on I didnt want to replace a $140 partt so, I got some MAF cleaner and cleaned the wires and they looked good afterwards. Still stalls out. So now I'm thinking fuel injectors? I got some injector cleaner and put that in the gas tank gonna see if that makes any improvement. But fuel injectors for my car run 50 each and I've got 6 of them. Is there any way I can check to see if they're bad? Any idea as to what else it could be?