need help, car dies.

ihave a 93 maxima with the V6 3000 24 valve engine. It has 244,000 miles and it starts getting sluggish and than dies and comes on and dies. At first it was at high speeds and now at low speeds. It doesn't do it all the time, but may be every other day. It has a 5 speed so I just put it into a lower gear than it takes off, but if I floor it it might die again. When I get it to run if I just baby it along it runs. I do know that one of the back valves seems to be bad from what the mechanic says. That is 1400 in just labor to fix. Car doesn't smoke. Could this be the cause of it just dying? I would hate to spend this money on a valve job and not correct the dying. It does have a strong exhaust aroma also. Any help or advice would be appreciated.