OK, here we go. This is 13.1.1986 until further notice; turns out I don't have 1987, but it's likely exactly the same. Trains in BOLD run every day; others are just paths and may or may not run.
Down trains:
00:25 Shelton - Abbey - Galway fertiliser PATH dep. Mullingar 05:50, arr. Athlone 06:46 Loco: 001
09:35 Shelton Abbey - Ballinasloe fertiliser PATH dep. Mullingar 15:30, arr. Athlone 16:41 (Stop scheduled moate 16:07-16:230; reason not apparent, probably to fit in with paths west of Athlone) Loco: 001
18:50 North Wall - Ballina Asahi Liner Pass Mullingar 20:43, arr. Athlone 21:36 Loco: 001
21:45 Connolly - Galway Mail Dep. Athlone 23:07, Moate 23:36-23:51 (Crosses up train), Athlone 00:16. Loco: 121 On Saturdays, this runs earlier, dep. Connolly 19:50, dep. Mullingar 21:14, arr. Athlone 22:15
Up trains:
22:35 Ballina - Shelton Abbey Empty Fertiliser PATH dep. Athlone 00:40, arr. Mullingar 01:30. leaves at 02:25. Loco: 001
02:25 Ballina - North Wall Asahi Liner (Tues - Sat) dep. Athlone 05:27, pass Mullingar 06:19. Loco: 001
22:00 Galway - Connolly Mail dep. Athlone 23:20, Moate 23:45-23:48 (crosses down train), arr. Mullingar 00:18 Loco: 141
SUNDAYS
No regular trains, but three DOWN paths and two UP paths for Knock specials from PEARSE, motive power not specified for any of them.
Note: Two down paths for ferts, butn only one up; the other obviously going via Portarlington when it runs. Also, the WTT shows a 121 for the down mail and a 141 for the up working. Of course, these could be interchangeable.
These two mail trains, which crossed at Moate between 23:36 and 23:51, were the only trains on the line by then (and for quite a few years earlier), which carried passengers.
Hope this helps.
JB