What could be wrong with our car? For about two months it would die every now and then when we would try to take off from a light or stop sign and now it won't work at all.

A loud clunking or knocking sound is often a piston rod,-- broke, wrist-pin in piston broke, or bottom bearing spun. The bearings come in two halves that go around crankshaft journal and rod is on one side and crank on the other. If one spins out of place from wear or lack of lubrication it creates a space and there is your clunk

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Cut your loses and junk that thing. Half of the problem questioners are Neon owners. Chrysler should be shot for putting such a P O S on market.

and here is Idle air control valve