TF 3 litre diesel Owners

I have a 2002 Rodeo I purchased recently to replace my 1994 Rodeo 2.8 diesel. The 3 litre diesel has good urban performance but performs poorly on the highway dropping 10 to 15 kph on hills. So its been dyno tuned and all is good apparently, I did fit a steinbauer chip. This gave considerable improvement in power but the vehicles hill climbing performance is the same. By comparison the 2.8 ran up most hills at 100kph although it was much slower getting going. My vehicle unlike the RA does not have a EGR or catalytic converter. It has new fuel and air filter.
The Steinbauer is supposed to lift power from 96KW to 115kw but it still assaults hills like a non turbo diesel. Staying in fourth gear which gets the revs back up to 3200 where the 2.8 runs at increases noise but still it will slow on most hills.
So maybe this is as good as these things go but I would like to hear from those who own or have owned these to verify that this is in fact the best these run. Its difficult to understand why it will go well around town and drop its bundle on the highway as its difficult to sit on 100kph unless on the flat ground.
My understanding is it doesn't need injectors as its only done 135000kms and at $330 each I am not inclined to replace them hoping all will be fixed. It does have a MAF sensor but I believe when these play up it will be loss of power at the bottom end.
It did come up to spec on a Dyno so maybe another single or space cab ute needed.
Experienced or knowledable input would be appreciated........Peter