Hi guys...Need some help with my emission...

Got the code 44 up for a while now...The service engine soon light are not flashing all the time..

But it come's on after driving for a while and is flashing for about 20seconds and then stops flashing...suddenly it can come on again..
I have checked the book of what to look for on code 44 but haven't figured it out yet...Could be a lot of things so just want to check if anyone of you have had the same problem???

Changed my O2 sensor but still the same problem..

 

There are many possibilities, including external and internal vacuum leaks, improper float level in the carburetor, incorrectly adjusted carburetor (including the TPS and rich/lean stops for the Mixture Control solenoid), intermittent electrical connections, air leaks at the exhaust manifold or pipe, air injection diverter valve leakage, and probably others I've overlooked.