Pulsating idle at any time

[atman100]

I have a pulsating idle problem that kicked on the "Engine System Service Required" message in the little window to the left of the steering wheel. It was threatening to stall the car but the computer perhaps jacked the rpm up only to have it drop back down to 400 . I replaced the MAF sensor with a new Cardone one and it was still happening . I replaced the O2 sensor and it was a lot better but still happening complete with the warning. When the code 2188 or 2178 (Bank I , idle too rich ) and code 130 (Improper voltage at MAF sensor ) is shut off, it comes back on within three minutes. The removed 02 sensor has white mineralization on it but with a coating of black soot on top of that. I can't visually see any air leaks but there is one tube leaving the right side of the intake manifold and splitting into two tubes and the "Y" connector is loose on that tube . On the major air tubes there is a varnish of hard dry oil on the couplings but no apparent fresh oil, cracks or looseness. There are no codes regarding the throttle module What comes next in the "check it" hierarchy ?