I've never experience this. My recommendation is to check if dropping to 4G helps. I usually do that when I'm in a congested area but given your area and bars, I have a feeling theres something going on with the hardware you're interfacing with T-Mo with.
I've had nothing but great experiences with T-Mobile - but, I do say that as someone who left Sprint.
I've had nothing but great experiences with T-Mobile - but, I do say that as someone who left Sprint.