panning animation with text across the screen has s strobe effect and not readable

It looks like you are experiencing JUDDER. The frame rate and the speed of movement combine to create a stroboscopic effect on the text. The solution is to move the text at an even number of pixels per frame. The whole animation shows the problem; the text just makes it more apparent. I would keep motion blur turned on but make sure it is set to 180º and -90 in the Advanced tab of Composition Settings.

Cinematographers also have this problem when panning a camera. It's called Critical Panning Speed, and a chart in the ASC Handbook tells you how many degrees per second you must use with each lens. I've been dealing with critical panning speed for my 4+ decade-long career.

I use an expression to create the movement. I like about 6 pixels per frame for 30 fps video. Here's the expression for position:

moveDistance = 6; //speed in whole numbers
startTime = time - thisLayer.inPoint;
frameCount = startTime / thisComp.frameDuration;
pixPerFrame = frameCount * moveDistance;
[value[0] - pixPerFrame, value[1]];

"6" is a good speed for an HD comp, and "12" would be the equivalent for a 4K comp. Those numbers would give you the same speed across the screen.  

I hope this helps.

Turn off motion blur and check the continuous rasterization:

https://helpx.adobe.com/after-effects/using/layers.html

Mylenium 

Without exact info about your project, how it's keyframed, what options e.g. for motion blur are used and so on we can't really tell you much. that aside it simply sounds liek the typical "judder" associated  with scrolling texts for instance when the timing does not line up with the motion. This is a common problem and you can find tons of info on how to improve and fix it such as simply making the text go slower or faster to coincide with even frame intervalls, cranking up motion blur, applying addition directional and motion blur effects and so on. either way, for more specific advice you have to show us what you have with at least a screenshot.

Mylenium