Smokin J's BBQ IL -Tough Skin Issue

I have a new pellet smoker and have been playing around with chicken thighs for several months. I like to smoke at lower temps (150 degrees) for 30 to 60 minutes and then turn it up (225 to 250) for the last 45 minutes or so.
Every time I have done this the chicken thigh skin is tough and rubbery.

What am I doing wrong?

You'll never achieve crispy/crunchy skin at those temps. If you don't eat the skin then it's not any issue. Nothing wrong with smokin at the lower temps but you'll need to do something else for the skin at the end of the smoke/cook. You can grill them, pop em in the oven/broiler, use something like an Infrared roaster, or bump up the temp in your pellet smoker. I would think maybe 400º for a few minutes near the end would crisp up the skin. Temp might be wrong but I'm sure others will come along soon and give you more info.

When the chicken hits 150 IT, I crank up the heat to 375-425 (depending on the needs of whatever I'm throwing on next) and then take it off at 165 IT.

def higher temps for a crispier skin..try cooking the chicken skin side down for 5-7 mins over a direct heat source(400 or so), then finish off low until the 165IT. If you like the low and slow approach send me a PM and I have a simple comp style chicken thigh recipe for "bite through" skin. Good luck!