Car cuts out

[Bryanatkinson]

Looking for help anywhere I can. Being new to the hobby I struggling with many different issues. The latest is that one of the cars in a race will start to cut out. All cars run strong at first then one or two cars, (almost never the same car) will cut out then go, making it impossible to race. I have jumpers installed and I'm getting 6.4 VAC on every section of track, both lanes. Both power supplies are putting out 32.5 VAC. I would be grateful for any advice.