Is my engine F'd? (post timing belt replacement)

[fanofe30s]

To start, my engine has been running strong and great. No problem starting up within 2 seconds, not running rough, no problem idling, no smoke or anything; it was perfect. Since it's been about 5 years since it was last changed, I decided it was time to change the timing belt.

This is the first time I've undertaken this, so I made sure to pull up a couple different guides. I spent about an hour making sure the camshaft and crankshaft were both aligned with one another.

Now when I start it up, it takes about 5-10 seconds, if I don't hold the gas pedal down, it'll go to ~1500 RPM like any car when it's initially started up, but it slowly dips down until it dies while in neutral, there is white smoke coming from the exhaust, and it runs really rough.

[Kershaw]

check for vacuum leaks. sounds like you have a big one.

and the camshaft should be aligned with the mark on the head and the crank should be aligned with the mark on the block. im sure that's what you meant, though.

[jlevie]

I agree, you probably have introduced intake leaks when changing the belt. A smoke test will find the leaks.

[Exodus_2pt0]

Vacuum leak makes sense. If you hold the pedal slightly does it stay running?

If your timing was off bad enough to bend valves it wouldn't start at all.

Also, whenever you replace a timing belt it is always good practice to turn the engine over 2-3 times and make sure the marks line back up. When you apply tension to the belt it will sometimes reveal that you were actually 1 or 2 teeth off.

[fanofe30s]

I appreciate all the responses guys!

I re-checked the timing belt to make sure everything was aligned properly, and it was spot on. When putting things back together, I noticed that the bit that's right by the idle control valve (not sure what it's called) was a little loose, so I tightened that up. As a result no more smoke!

It was still running weird and taking a while to start up, so I asked my dad to listen to it. He heard something wrong near the camshaft. We took a look and one of the rocker arms is either loose, or just plain broken. He held down, and the car started right up, and sounded normal.

Is it possible to replace just that? Or would I need to replace anything else?