85 GMC truck hesitates on hills occasionally

[gcoon]

Did a test drive around the city going up lots of hills and seems all right. Will do a test drive out to the mountains this week. The dash switch was not always working when switching to the left tank you could not hear the motor or it would be for a short time. I pushed on the connector at the back and the switch broke apart. I replaced the switch but don't know if that was causing any problems.