I've noticed some rough takeoffs in F-4s, fully loaded, without afterburner (gotta save gas). You'll have to pull back a little forcefully to get the jet off the deck, but you're about a half-inch of stick movement from stall. Overdo it, and you can depart and come right back down into the runway. As it is, most times you're hanging on the stall, feeling the buffet.
Setting up your game to use pitch "trim" could help with easier rotations/liftoffs. I noticed flying the TMF Crusaders that about 5 "clicks" of aft trim will let you have a nice, smooth rotation - with or without using burner.
For your issue, maybe a little forward stick trim will help.
Set up trim by going into one of the config files and adjusting the keyboard inputs for pitch (and roll - helps trim the jet after you sling off some ordnance). Basically, you want to disable the re-center feature so that once you hit the key to deflect the stab/ailerons, it stays in that position. Adjust the sensitivity to your liking - smaller values are better for the fine tuning, but too small and you'll be trimming forever. I don't remember all the specifics, but I think it's in the KB somewhere.