Hi there, a friend showed me your problems earlier today, hopefully you have fixed your issues already. If not have you checked the P2 system double check valve, located on the main gearbox decking? If this valve leaks it will leak air from the engine being tested in to the other engine and you will T4 limit! Also if the P2 system bleeds from the compressors are leaking at the banjo gaskets then this may also be a problem.
You can blank off the P2 system from the ports on the compressor and test the engines again to be sure, (you shouldn't fly the machine like this but instead load it with weight so you can pull power without getting airborne).
The acceleration differences are because the governors require setting up better, this is done on the beep motor cam or slot dependent on version. Again this is on the gearbox decking on the right hand side of the aircraft.
Let me know how you get on, good luck.
THOS IS ADVICE ONLY AND ALL MANUALS AND AIRWORTINESS REQUIREMENTS SHOULD BE TAKEN IN TO CONSIDERATION!!