When driving around town without the a/c in 95-100 deg weather, temp. gauge is normal. If a/c is running temp runs hot. I have changed the fan clutch, water, pump, t-stat, and radiator flushed professionally, but truck continues to run hot when a/c is on.

Likely, you need to replace the radiator, or have it rodded, due to phosphate scale buildup. Only use a 50/50 mixture of manufacturer-recommended antifreeze and distilled water, in the future. An IR thermometer may show relative cold spots in the radiator.

We'll have to assume you did the obvious radiator fin cleaning on both the radiator and the condenser, right?

If so, then there are only two things left--the radiator and the baffles/shrouds around the radiator. Believe it or not, if the baffles or shrouds are missing, broken, or out of place, it can REALLY affect airflow through the radiator.

TX makes a really good recommendation with the infra-red themometer. You can pick them up cheap (around $30 for a good one). Then point it at several places along the water route and the radiator. It will immediately show you the spots that aren't cooling properly.