Problems with 5.0 please help

rusty muffler bearings, they will do it every time, and the smoke is caused by worn pistion return springs....dude from your descripition it could be one of a hundred things be more specific, is the car running okay does it burn oil??? that could be your smoke, the starter may be the problem or it could be the battery, or it could be the engine is running poorly and is starting hard, like i said if you want help be more specific

The clicking/rattleing noise on acceleration is probably pinging or pre-ignition. Usually is is caused by too much spark advance or running a lower octane gas than the car's tune requires. The stock timing is 10 degrees BTC, and advancing it to 14 degrees BTC is common practice for more performance. Try running several tanks of 93 octane gas and see if it improves. If not then check the timing.

Since you seem to be new to the Mustang arena, here's how to do it.

Paint the mark on the harmonic balancer with paint -choose 10* or 14* or something else if you have NO2 or pressurized induction.

Remove the SPOUT connector (do a search if you want a picture of the SPOUT connector) It is the 2 pin rectangular plug on the distributor wiring harness. Only the EFI Mustang engines are supposed to have a SPOUT. If yours is not EFI, check for a SPOUT: some poorly done carb conversions will retain the EFI ignition. If you don’t find one, skip any instructions regarding the SPOUT
Warning: there are only two places the spout should be when you time the engine. The first place is in your pocket while you are setting the timing and the second is back in the harness when you finish. The little bugger is too easy to lose and too hard to find a replacement.

Connect the timing light up to battery & #1 spark plug.

Start the engine, and loosen the distributor hold down with a 1/2" universal socket. Shine the timing light on the marks and turn the distributor until the mark lines up with the edge of the timing pointer. Tighten down the distributor hold down bolt, Replace the SPOUT connector and you are done.

Is your starting problem one where the engine does not crank over or one where the engine cranks OK but will not fire off and run?

I think you have the same problem I am currently fixing.
The tranny is leaking from the front bearing retainer seal.
And the throwout bearing is shot because of it.
The smoke would be from tranny fluid being thrown onto the exhaust and burning off. You don't see leaks because it will only leak when
your driving. Look at your exhaust pipes, if they are covered with
burnt on crap, then that should be your problem.