as the title states I could use some help.
this is an older model redcat dpx 250 2x4, rear wheel drive only.
suddenly is started running rough, when under load, basically when just driving it. it acts like a cylinder misses randomly,

any suggestions on what to look at first would be helpful.

Tomorrow I'm going to look and make sure all of the electronics are dry, it started after I sprayed off all the mud.