Runnin rich

Okay, ive got my bronco running way too rich. Its fine in park and neutral, but when put under a load it just boggs down really bad. I pulled the plenum off and the throttle body and I had excess carbon built up. When idling, the engine light wont come on, when you rev it up, it will. Its getting so much fuel that its backfires threw the throttle body.
Do to me not having the nessasary tools, its become quite hard to diagnose.
would ya'll kno?