I have a 1991 Dodge B250 van, and sometimes my spedometer won't go above
40 mph no matter how fast the van is going. Whenever this happens, the engine starts running really hot. I don't have a tachometer, but it feels and sounds like the rpm's are high, but I have no problem making highway speeds. It's an intermittent thing, and happens maybe one time out of ten that I use the van. Any ideas? Thanks!