Thanks everyone for the comments and thoughts. Before starting the A/C the line voltage at our whole house power protector reads 123 V, under load it hovers around 115 - 116 V. Yes, I am using a clamp on amp meter at the breaker box clamping on the AC lead.
As I said, it would run for several hours in the morning when the temperature is only 85 - 95 (only???).
The coils and fins are clean, but some of the fins have gotten bent (maybe a too low tree branch?) The original breaker was 15A, so I replaced with a new 15A.
If anyone has additional ideas, I'd be happy to hear them.