1989 Fleetwood Jambo Ford E-350 with 460 engine question

I use to have several 460's and I agree with oldwiz. Replace that TFI module. Something else that really helped me was clean the radiator inside and outside. I actually removed mine, laid it on the driveway, sprinkled it with dish washing detergent, then put the hose on it real strong. I was amazed at the amount of dirt that washed out. When I put it back in the temperature gauge was lower on the dial about a 1/16 of an inch.