Lately my 92 GXE auto tranny, started to vibrate at idle speed and it was even worse when the transmission selector lever was on “D”. I replaced spark plugs, fuel filter, air filter and checked the spark plug wires impedance and it was OK so I did not change them. It got a little better but definitely was not as smooth as it used to be. I went through the stickies and through several posts on this forum, I have found some tips to troubleshoot this issue, so I started to look for a vacuum leak. All the little hoses were not leaking, so I disassembled the air filter housing because I thought there could be something clogged. I have found that there is a kind of gasket in the union between the air filter housing and the air pipe (the one to the left of the MAF sensor); it was in very bad shape totally worn. I could not find a replacement part (I’m in Mexico and there are no suppliers for maxima parts other than a dealer) so I rebuild it with gasket maker (the one that is sensor safe), assembled everything back together and the smoothness came back again, no more vibration at all.

I hope this helps others.