As per
@Greybeard33's point, though, it isn't Oxford Road that is the bottleneck westbound, because the trains have already all stopped at Picc P14 and thus are leaving spaced out by the dwell time at Picc anyway. So I'm not sure that there is any need to do that nor anything to gain from doing it, as they would (eastbound) just be queued up for Picc P13 anyway, or (westbound) spaced properly.
What is needed is to reduce the number of trains through 13/14 until such time as the service stabilises, and one way to do this in the short term (and free up two Class 185s for strengthening) would be to remove the two Ordsall Chord services and send them back into Picc to terminate in P1/2/3, and to add 2tph of Class 319 or 323 operated dedicated airport services from P11 or P12 in their path. What other options might there be to achieve this? I guess the rather silly Liverpool-Crewe service could be split into Liverpool-Vic and Picc main trainshed-Crewe?
Additionally, as per my other posting, Northern (and if applicable TPE) need to rejig their crew diagrams and route learning so there are no planned crew changes at any Central Manchester station.