ok, nuke, couple things- you are absolutely certain the water pump you have is for the DOHC? cuz i got one installed some years ago on my DOHC that was actually for the SOHC... had a LOT of warm running times with that water pump and didn't know it was the wrong one until it chewed up the timing belt, left me stranded and cost me almost 900 bucks...

ok, that's that one...

i am still thinking you have a cfm issue with that new fan, maybe the motor isn't getting enough power, maybe the fan just doesn't pull enough, i don't know, but basically, when you speed up and the coolant gets warmer, it's because you need more airflow...

ok, so, you took the winch bumper off and it ran cooler? ok, i'm trying to figure out how one has anything to do with the other, but it's possible with the flat face of the bumper that it's forcing air out and around the grille instead of into it, which, this would be the first time i've heard of it, but it could be cuz everyone else with the bumper still runs their clutch fan... maybe i should do something about redesigning it somewhat for better airflow... reason i build them the way i do is so the winch will sit inside and out of the way of the grille, but it is still 8" tall and could very well block lots of air...

here's what i would do- put the clutch fan back on, test it one last time, with the winch bumper on... if it runs fine, get a higher cfm rated electric fan, to be honest, i'd be using one rated at least for a v-6, if not a v-8... it's like lt. ripley said... "it's the only way to be sure..."