I ran into this problem about two days ago on the way to work. It has me a little worried so I'm hoping someone could offer some explanations. So when cruising at about 45-55mph, the engine speed "twitches". If I watch the tach,the reading will jump by like 300rpm and then go back down. It happens most noticeable between 1.5k and 2k rpm at about 50mph. It only happens in this gear (4th?). Could there be something wrong with my transmission?

In other news, I installed all the lights I got from motorcepts. I've been insanely busy but I'm going to try to get pictures soon.

 

Have you had, or have you checked for a leaking gearbox sump?

Mine does exactly the same now after I had the sump pan plate replaced.

Mine is due to go into a gearbox specialist shortly so I am praying they can identify the issue and sort it without lots of £££££ involved. If your read around lots of people have had a similar problem which has been solved in a variety of ways from a software install through to a full gearbox replacement!

NOTE - I would recommend checking the sumps not leaking (need to drop the engine pans to see it) as catching this early is better than waiting for the box to go low on oil.