Ford Repair: 1992 Mercury Tracer 4 cyl 1.9 L, mass air flow sensor, mass air flow

Question
163000 Miles,Car starts right up, in park rpm is at about 750,(feels normal) when shifted into drive or reverse,  rpm drop to 650-600 feels like she wants to cut off but does not, same thing when I stop at a light. passes KOEO/KOER self tests, KOEO continuous memory had a code 122, which after being cleared never came back. All KOEO/KOER tests are good. Just replaced O2 sensor & TPS, plugs and wires are new. re-checking all the vacuum lines and Etc. Any ideas?? or direction should I recheck the timing?? Thanks, Brian

Answer
Hi Brian thanks for asking and sorry about the delay. there are many possibilities. checking the timing would be a good idea anyhow. I would also look for some kind of vacuum leak, spray the intake down with intake cleaner or brake cleaner that will be an imidiat notification of a vacuum leak. Also inspect the idle air control motor, and the inside of the intake, make sure the mass air flow sensor is clean- this is located in the breather tubes close to the air filter. If you still have a problem get back to me
Good luck
Chris p