Barnstormer
I don't think that the F-111 would ever have any difficulties out running a MiG-21. A MiG-23, yes, but not a Fishbed. Also, the APQ-110 TFR was built by Texas Instruments specifically for the F-111, not the TSR.2.
You were correct that the F-111 was troubled (to say the least) in its early days, and the F-111C that the Aussies bought took 5 years to be delivered from the time it was ordered.