Blessings to all,

Ive came across a beautiful Q45, and I’m honestly in love! I had no prior knowledge cars whatsoever; but quickly picked up on my Q45! Recently I had some shifting issues; car seems to jerk everytime it shifts from 2nd to 3rd, and for some odd reason I thought I could fix it by buying a new TPS; i replaced the TPS and didn’t fix the shifting issues but found the car had smoother acceleration; fast forward a few weeks I clean the Throttle body and found a stored pending and confirmed P1120 Secondary Throttle Position code along with a P1400, and P0400; so far after the New TPS I’ve replaced my EGRC SOLENOID and EGR valve, EGR purge valve and new MAF sensor; I’m wondering besides the faulty slipping transmission what can I do for my P1120 as well as the EGR codes!

About the trans, I did the Auto Shows for years, I talked with dealer techs across the country, we had them at every show to disable things for the show, I could never get the same answer on transmission service, some said do it regularly, others said don’t. Since there’s a drain plug in my Q, I did just the fluid, another can I did have luck changing a plugged filter for smoother operation, but if it was plugged, that meant is was full I’d the band material and the trans was on the way out.

These cars are very finicky about transmission fluid levels. I have done what's in the manual and I still have the 2nd-3rd odd shift especially when cold. It gets much better to almost non-exisistent when hot. This leads me to believe that its a level issue and I need more as ATF expands when getting warm. I do think there are worn bands but have added ATF additives such as Lucas for the mean time. My fluid is clean and doesn't smell burnt so who knows.

Have you looked at the factory service manual for trouble code diagnostic info?