dtc p0171

hello, i need some help with dtc p0171( bank 1 lean) i examined the air intake before and after the maf and map sensors, ck for disconnected vaccume lines(as best as i could...geese can gm get ant more tubes wires and rubber lines in this engine compartmene?!?....lol) and cant find any obvious s/s. can any one give me a push in the right dirrection on what to check? please. im now carefully and gingerly going to clean the map and maf sensors and confirm that there are no leaks, cracks ect. do i need to ck fuel pressure? just a thaught....i just put lower profile tires on....225/60/16 to 225/55/16 i think it was just coinsidence but could that cause a p0171 to be stored??i did erase the dtc and the light did go on again. well ill leave the rest to you guys/gals cuse 4 eyes are better thjan 1. peace and thsanks again.
dave

Air is entering the engine unmetered, you have low fuel pressure, a skewed o2 sensor, tires have no affect. BTW, post year and engine. Also, I lived in Bellmore for 30 years.

hey old neighbor, thanks for the reply. sorry i didnt include the eng and car. the engine is 3.8, 1998 monte. btw off topic real quick .......if you remember gilwilders farm on jreusalem ave.......well now its co-ops ) 0:

Yeh, I've been in the area several times, my daughter lives in Bethpage.

ok, there is a vaccum port on the intake manifold that biforcates. one goes to thfuel regulator,the other i dont know. i taped it at all places and the mil went off, i think thats the problem,and get a new part from the dealer