MX 5 drives like a tractor

Hello you love, since Saturday last week my MX5 BJ 2000 occasionally does the following: If I let him go he runs extremely restless (the whole car shakes) and he rides like with the handbrake tightened. Oil and cooling water are fine. He was normally waited in May and he got new brakes 6 weeks ago. He smells like hell if you keep driving him and gets more and more difficult. The rear left wheel box gets very warm, but visible nothing is normal optically iches. So far, after a certain service life, he has always thought about himself and ran perfectly normal, which is not very helpful in the workshop (where no problem, none can be solved) I am perplexed and am looking forward to expert opinions / tips!