can this code be caused by installing a new idle air control valve? i
thought the iac just controlled the idle . i had a code p0306 misfire on
cylinder six and found out the morons that worked on my 98 stratus had the 2
front spark plugs only finger tight,this caused the actual plug wire to pop
up an inch off the spark plug and when i pulled out the plug wire for the #6
plug it was filled with gas. i then pulled the upper intake manifold and
ended up finding the back 3 plugs were loose too. i torqued all of them and
put the intake manifold back on,using the same gasket, it looked brand
new,they just changed it. now i have this new code i didn't have
before,p0171. they put in a new downstream O2 sensor but the 2 in the
exhaust manifold are original,but no codes for any problems with them? does
this code lean toward a vacuum leak of some kind?  thanks for any info Randy