bad sensor or engine mounts?

I have a 2001 gt grand am.

two weeks ago, the head gaskets went out. so i replaced them. i got the car going and now it clunks when put into gear or shifting. It didnt do that before. I cant tell if the mounts are bad. they dont look cracked or anything. The engine does move quite a bit when i put it in gear. Now today its making a strange rattling sound thats comming from some where around the bellhousing on the trann. also sometimes at startup it sounds as if i am turning the starter over too long, but i am not. it makes a pulsing clinking sound at the starter. I am going to take a look at it some more today. I was wondering if any one here might have had this problem before or if any one knows what is causing this to happen. Is there a sensor or something that could do this? any suggestions would be great. the engine is the 3400

I can't think of any sensor that would give you the symptoms your describing, if the engine is running smooth then i'd guess its a motor mount or something else. Im not positive where they hide the mounts on a 3400, but the basic concept is to have one on the tranny side, one on the belt side of the motor, and one to keep it from rocking back and forth (looks like and 8 or commonly called a dogbone). Check out the dogbone, make sure you tightened up the mount & it has both bolts in it. When inspection a motor mount its unusual to find the broken, most of the time its the rubber between the metal parts that breaks down letting the metal touch together. The dog bone might be on top of your motor in the center connected just above the radiator.

Other things to check, since you talked about the starter making noises when you start it, did you remove the starter? If you did sometimes they shim the starter to make the teeth fit into flywheel better, if you didn't remove this then don't worry about that. Other possibilites could be a loose flywheel or the gear of the flywheel moving on the flywheel (but don't jump to this conclusion), some are held on by welds & some are an interference fit, which means when they make them they heat up the gear side, cool the other, then put them together, when they both come back to the same temp they don't move. Could also be a starter going bad & the gear staying out too long.

when I broke my trans mount, under the car, the motor rocked BAD! Just the rubber bushing was gone. Not Good.

If I shifted manually(in an auto) it would hit throtling up or down, and when I stood on the gas. A pita to change.

But I dont see that linked directly to you changing the intake gaskets.

thanx for some info . if you hear anything else , let me know. pm me.
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thanx again

Is your engine idling to fast? Sometimes the starters break and the gear does not return all the way and it contacts the flywheel teeth making a rattling sound. Sometimes it will do it if you turn to the left or right quickly that will make the gear slide out and contact the flywheel

it doesnt idle fast at all and it makes the sound all the time. still cant figure it out, except it doesnt do it when its cold