Shaking at speeds over 65 on accelerating, now engine light on and ECO not.

What is your question?

Purchased 2 mos ago, on recent road trip, car began to shake when on cruise control over 70mph and on acceleration over 60mph. Then engine light came on and ECO light not on. Is this an engine mount or torque converter issue? Dealer says they ran codes, nothing came up and so they can't fix it. That sounds like a bogus answer. Car is at 35940 miles so still under main warranty but also certified used. Please help!?