I had the same issue... I was running a napa mini starter on my t5 tans.
I would not call it heat soak...more like just POS starter that doesnt have enough torque to turn over a warm engine.
I replaced it a year or so ago with a ford racing mini starter. Its awesome. It doesnt care if the engine is hot, cold, flooded, high altitude, sea level, or weak battery. It will %*$ing crank anything over. No heat issues at all ever... even when its a 115 out.
Im 95% sure this is the one i got