Van overheating

I got a 98 Ford E150 Conversion Van with a 5.4 V8. It starts to overheat when under load & the outside temp is high. I can turn off the A/C & drive easy & keep it from overheating. I’ve had the engine checked & the pressure is ok, so the head gasket is not leaking. Themrostat has been replaced & is working properly. Also the fan clutch is new. Any ideas? I don’t want to waste the money on a new radiator if there is something besides a plugged radiator causing this like a sensor or something I haven’t been able to figure out.

It’s probably a plugged radiator. But first, try cleaning off the rad, it may be covered with lots of bugs and debris. But really, I’d be thinking it’s a radiator problem.

Have you flushed/replaced your coolant recently? Could be a waterpump with a degraded impeller, too.