Hi My 2000 4runner has the stock radio with the CD at the top and cassete at the bottom. The problem is the left channel keeps cutting out. Might be a heat issue. Always works when first turned on but then will cut out and then come back on. Times varry. Is the amp seperate or is the whole radio integrated? Any other thoughts. All of the left speakers cut out so I don't think it is a speaker issue Thanks and also will the later model radios swap with out too much trouble if I need to replace this unit. Richard