3.8 1999 P0171 & P0174 error code

[db35162]

Ford windstar 1999 91000 miles, Runs great untill the temp guage just starts to move and this is only if I am at idle, Rpm's drop and very rough idle so that I have to put it in nuetral and feather the gas to keep it running but when I start moving it starts off sluggish and then it snaps out of it with in 100 ft. and runs great. I got the van when my mother in law passed and the check engine light was on and still is, this will be 4 years now. I changed 2 of the up stream O2 sensers from a mechanics suggestion and reset the PCM and the light stayed off for a day but the next day it came back on , same codes. I have to run no less than 91 octane or it will ping. I know this is pointing to a vacuume leak or something wrong in the EGR system. Today I just cleaned the MAF senser by spraying the electronics cleaner at the wire element in the center of the little MAF sensor. I let the cleaner soak in for several minutes, then give it another shot of cleaner and let it dry. I won't know if this helped because I have a half tank of 93 octane in it. I did find a the vacuum hose that connects the fuel pressure regulator to the intake manifold was swollen and leaking vacuum where the hose connects to the manifold. I fixed that leak and ran it on 89 octan with no pinging for 2 weeks untill I started to use the AC and could hear some pinging so I went back to the higher octane. It does use oil and it is not burning it but there is leakage on the intake but very little, not enough to account for the amount lost. Last night I pulled the PCV vacuum line and there was a little oil in it (brand new PCV valve) and the hose connection to the manifold seems very lose, I think I will put a ty-rap at that connection. Also the coolant turns brown or rust colored and it's not oil and there is no sign of coolant in the oil. Me and my nephew are doing a intire coolant system flush and going to take a serious look at the intake manifold today but if anybody has any suggestions that would be great.