I have a 4" 2 wire sub pump 150' down with black poly up pipe. It's been in the well for about 2 years. Recently, it started running for about 15 seconds and cutting off before the tank reaches cutoff pressure, then after about 30 seconds it will start again. It does this over and over. I checked voltage at the well head and it's 246 running and remains 248 when the pump quits. The pressure switch never opens since the tank never reaches cutoff pressure. Hot leg to hot leg measures 3.7 ohms including about 200' of wire. No reading from either lead to ground. I have not pulled the pump yet. I think that the thermal overload is tripping and when it cools off will start again. Can there be another cause for this behavior?

i'm a city boy and know little about wells. BUT, the is a nipple that the pressure switch screws onto. could it be mostly clogged so the switch doesn't get a good pressure reading?

You need to take an amperage reading. What you describe is a thermal cutout of the motor as it overloads. Typically, this condition usually results in 'no water' since the pump cannot keep up with demand in heavy usage.