Fuel filter change on td42

[SKID]

I know this is an old post sorry, I have read many places about "the tiny thimble size filter" Just replaced my filter and added a water separator type one with a glass bowl as a pre filter to the standard one, I have been experiencing when I really give it berries up a hill from around the 2K-3K rev mark it hesitates as though it is starving of fuel, But if I rev it when I'm parked, it revs out well up to the 4K mark with no hesitation. I followed the instructions here today to try and get the "the tiny thimble size filter" out but it appears there isn't one in there as I can poke a bit of wire about 2-3 inches down the hole. I've only owned the truck for two months, it was originally a 200 GU 3Ltr but when the guy blew the motor up he put a 1990 silver top in. When I was getting the air con re-gassed 2 weeks ago the guy made comment that the injector pump looks new, I've read that some of the later model cars don't have that tiny filter, if the pump is in fact new could it be a case of if or when it was reco'd that they never put the tiny filter in? Any advise or suggestions would be greatly appreciated....

[SKID]

I already had the feeling of fuel starvation before I added the other filter and replaced the existing one, putting the foot down I was lucky to get 3000RPM out of her
After the initial priming of the fuel and the hand pump is hard I know with in a short time after driving to say the shop and back that I can usually get a further 5 or so pumps before it goes hard again, is this normal?