ATF is basically Seafoam (in practice- I know they're not actually the same). Maybe better. I've never had occasion to use the latter, but ATF does a great job of desludging engines without resorting to solvents. I've heard of it being IV'd into the intake as an induction cleaner, too, but that's a bit more doubtful...
Marine shops like to use ATF to winterize engines. Fill the fuel tank(s)and add stabilizer, connect a hose to the outdrive (or water intake), fire the engine up, bring up to operating temp, shut down, change oil and filter, fire it back up, check for leaks, rev engine to about 2,500 RPM and pour ATF into the intake (enjoy the white fog you create!) while keeping the revs up until about half a quart is consumed and then let the engine idle down and die. In the spring you change the plugs, check/replace the distributor cap/wires, change the fuel/water separator(s), clean the spark arrestor(s), connect the water to the inlet, fire the engine(s) up and let the white smoke belch forth until it clears up, then complete the tune up.
There's lots more to winterizing but the ATF part was always a blast. Former marine mechanic and service manager here...
Regarding the black smoke and fuel injection: Getting fuel injection to play nice with huge overlap (reversion) leads to all kinds of fun, hence the smoke on fast rigs upon sudden, hard acceleration. I've seen some pretty cool sights like how low RPM reversion on a four way Weber 48IDA system with a huge cam would spit A/F mix up out of the throats and suck it right back down on sudden acceleration without missing a beat. Getting fuel injection to deal with that takes some skill.
The best advice is to just stay in the throttle until it clears up!
