97 Diamonte 3.5 L

Start it up, runs fine for a few seconds then idles up fast. Stabalizes again for a few seconds then fast again. Does this 4-5 times then dies.

The car was recently brought to me because of the inconsistent idle but I didn't have time to look into it. Then his timing belt (stationary) pully and water pump locked up. When he pulled it back I rotated the engine by hand to TDC, the cam sprockets weren't perfectly aligned (one was a couple of teeth). I replaced the pump, pulley and belt, lined all the marks up and got her fired back up. Has a light peck near the #1 cyl but otherwise sounds great until it idles up and down (then dies).

Couple of questions...

1. If it had incurred any serious damage when the pulley gave out (bearings literally separated from the wheel leaving slack in the belt) wouldn't it have some terrible noise now? Owner was not sure if the pecking noise was there before.

2. I know it had the inconsistent idle before but it didn't die. The owner said he stripped a bolt out in the intake (air) on a previous repair (why he brought it to me initially). Would an air leak cause this much of an idle issue?

By the way, their is no MIL light on and no soft codes stored in memory.

I'm a little reluctant to fire it back up until I have a better idea of the idle / die problem (until I'm confident he didn't bend / warp a valve) especially sine I have very little solid performance history on the car.

All thoughts greatly appreciated.

only a guess could it be a faulty idle stepper motor ? thing that controls steady idle