overheating problem 1998 grand marquis

overheating problem 1998 grand marquis
i need help on a overheating problem on a 1998 grand marqius. we have replaced the radiator,thermastat, waterpump,electric fan,fan relay,and the car runs fine with the a/c on untill you get up to speeds above 60 and it seems like the temp guage goes to about 3/4 up and if you give it more gas it seems like it goes all the way up to hot. then if you slow down and turn the a/c off it cools back down. any suggestiong? thanks

  pureluxurylimos

I-N-T-R-O-D-U-C-E Y-O-U-R-S-E-L-F :banghead:

  99integra

Could it maybe have to do with the oil pump?

  99integra