92 LS 400 - Just started today, at any speed from idle/stopped to highway speeds, car won't accelerate and bogs down unless I floor it. When I do floor it, it jerks like it just suddenly got a blast of fuel and leaps forward. Then it's fine for a little while before it repeats the same. Almost all stops or low speeds cause it to happen though. Only flooring it will force it to accelerate. Anyone have an idea what might be causing this?