1996 f150 check engine light. po174 code

Hi, I have a 1996 ford f150 with 302 engine. The check engine light has been on for a few months. the first month I did not notice any change in the running of the truck. I took it to Autozone and they put there code checker on it and it came up with code po174. Not sure what the code means. Now the truck is not wanting to start. It will start but it takes a while and runs rough for about 30 Seconds and runs good after that. It is getting much worse and the last time I took it out I did not think it was going to start. I had the left side oxygen sensor changed a few years ago but not the right one. Any one know what may cause this problem? thanks!

I don't know what the code means, call the ford garage. You might want to put a new gas filter on, it might help?. Its easy to do, right under the drivers side by the rear wheel.

Thanks for your answer and time. I forgot to mention that I had replaced the fuel filter.
I cleaned the MAF sensor with carb spray cleaner and it is working great at this time. It starts right up and runs smooth. The check engine light is off at this time.
My son has a 1997 ford van with 302 engine and his automatic transmission was not shifting at the right times. He had the MAF sensor cleaned and his truck is shifting great now. That sensor seems to be a key player in the runing of the engine and shifting of the automatic transmission.

po174 too lean bank two(which means something on the passenger side is off key in fule dilivery) But if you check engine light is off i wouldnt worry about it unless you notice a difference if fuel consumption.