Check engine light came on and I got the error code p0172. Any ideas where to start.

what kind of car

what kind of carP0172 indicates that the PCM reached it's correction limit and can't take away any more fuel in order to make the car run properly. It's likely a fuel system problem, so starting with a fuel pressure test and a fuel injector leak down test to see if any of the injectors are leaking. That would also be a good time to check the fuel pressure regulator for any kind of internal fuel leak past the diaphragm.

It is a 1998 Chevy venture.

I checked the air filter, it was not too bad but replaced it anyway. In replacing it I noticed that the housing was not properly seated. Perhaps this leak was restricting airflow? After I did this the check engine light stopped illuminating and the DTC changed to a pending DTC. After a few starts it was then saved in Freeze Frame. I cleared the code and now have no codes or pending codes. There were a few monitors not reporting and I guess I will see after it completes the drive cylce (whatever that involves) if everything is OK. IF it comes back on I will look to the fuel system. Thanks much, I appreciate your input.