I just got my FD re-gassed today and when I drive it whilst the a/c is on, the engine seems to back off and on again at a fast pace ever so often. Say i'm cruising at 2000rpm, the car will set you forward, than back as if it rocking and than when I turn the aircon off, it's fine... normal?

Also, my FD is manual, but struggle to get my gearboc into first whilst is rolling... it can be done, but it needs a push which I don't do... bad synchro? In every manual I have driven, first gear can be accessed whilst rolling...

Thanks guys..

Dennis,

 

Not sure on your first question, sounds like something is not properly grounded or is running lean under E/L.

All FD manuals are hard to put into 1st except at a dead stop. It's normal.

 

At low speeds, the AC normally cycles on/off quite rapidly. It's really noticeable and annoying in 1st gear. Combined with the normal drivetrain slop, it feels just as you describe. Mine has done this since new - I took it in under warrantee soon after I bought the car new, and was told that there was nothing that could be done about it.
My solution is to slip the clutch slightly while driving at low, constant, speed in 1st gear to dampen the bucking.