2012 malubu won't start

Ok, here it goes my Car wonn't start running fine
yesturday, I disconnected ECM for about 10 min no
fix. I removed all fuses no fix, fuel pump just fine,
gas 3/4. Because I was so mad I was about to burn
it. So I try my remote start. It wouldn't even make a
noise so I got in and with the key it started just
fine. I try couple more time and at 3rd time
wouldn't start again. So I lock and unlock the car
with remote and started just fine. No codes no of
anything the only strange thing is RPM will not
pass 4 or (4000). Any ideas? Oh yes before I
disconnected everything did have ENG LOW PWR
on it. All that is now gone. Thank you.