What type of GPS?
How is your GPS set up?
It should output messages a 8 or 10 Hz (I think yours only output at 1 Hz)
Or you output too many types of messages (Will slow down Agio): V5.1.4 Release - #196 by BrianTee_Admin
Or your baud rate is tool low ( go for 38400 or more)
If you have F9p this might help: Ublox F9P - Config for rover - #73 by Jean and the rest of the thread.
You dont need RTK or IMU to drive a straight and stable AB line (but with IMU it can be a little better)
If you have IMU you can test without roll influence from IMU, by setting antenna height to 0 m