1999 Ford E-150 5.4L have replaced MAF, EGR Sensor, ran Sea Foam thru gas, had CATS checked and other things. When hot outside van still runs rough when cooler runs a lot better. Funny thing I found out yesterday. Run with air on or heater van runs worst turn off idles better and runs better. Take out on road 55 mph runs rough and misses with or without air or heat on.

 

One of the things you can check is the plus side of the battery and alternator side that supplies voltage to the fuse panels and the fuse panels themselves. Lately many of the assorted problems were traced back to the voltage supply to the vehicle and all it's components.
Many vehicles had a junction connection that took battery and alternator voltage and supplied it to the fuse panels. Any corrosion in that supply will cause a voltage drop to many parts of the vehicle including the PCM. There are many components that operate with millivolts and a poor connection anyplace in the system causes all sorts of problems. Check the connections thoroughly.