Knowing the quality of that ESC I'm not sure that it is causing your problem with the Acoms receiver. The cap I am running with my low end ESC is a 4700uf 10v rating, which seems quite bulky.

The theory I had re the transmitter aerial was due to how I hold the transmitter during use, as the aerial is practically pointing at the car which as I understand it is not good (at least that is what my wifi engineers tell me). By using the rotation feature of the aerial and it's multiple folding positions I was able to get the aerial into a near vertical position when the transmitter is in my "in use" position. The difference between the two aerial positions was what I tested last night and the it showed a marked difference.

I have also tested running the aerial inside the body and while I could get reasonable range it wasn't reliable during direction changes.

Best of luck.

David.