99 Grand Am Intake Gaskets Replaced New Issues

I have a 99 Grand AM Gt 6 cylinder. I recently had both the upper and lower intake gaskets replaced and the car came back from the shop with a new issue.

Its doing 2 things, Upon start up as the engine turns over, it shudders as it starts and

While sitting idle (like at a red light with the brakes on) the car has a vibration, like its not running right. Hard to explain but its very noticable to me when sitting still because it almost sounds like im on a tractor compared to what it was before these repairs took place.

Can u tell me what it sounds like they might have done to cause this while repairing the gaskets?

In addition to the gaskets, they flushed the antifreeze, changed the thermostat and on the ticket there was some kind of adjustment pertaining to the distributor cap.

Thanks for you help.

Have it scanned for pending DTC's. See if any P030x's pop up and report back your findings.

Your stumble could be anything from leaking intake runners, bad or damaged plug wire, or bad fuel injector. Or even worse, if they mixed up which push rod went into what place, they could have bent a valve.

Plus there is no distributor on your car, so I am sort of confused as to what they could have been talking about. Nothing even remotely resembles a distributor

I reread the repair ticket, and it says resealed distributor plug. Not cap, sorry.

Could have a misfire due to the distributor resealing, by opening it they might have damaged it, or damaged a spark plug wire or not plugged one correctly.

however... I guess they mean the coilpack...

They hooked it up to the machine and found no error codes.

Can someone tell me does the engine have to be unbolted in order to change the gaskets?

depend on what you mean by "unbolted".

If you mean: remove the engine from the car, it would depend on which gasket and the arrangement of the surrounding parts.

if you mean the bolts that hold the parts together, yes.

I guess what i mean is , do they have to raise the whole engine to get to the upper and lower gaskets then bolt it back in place. With no error codes coming up, i just dont understand what could make the whole car shudder when the engine turns over, and it wasnt doing this before they worked on it.

small gasket leak, damaged sensor, damaged wiring, misconnected sensor, dirty sparkplug, worn out sparkplug wires, .... lots of things can go wrong, including mis reassembled

I would like to add that i notice the vibration when the car is sitting still in drive and put it in park and the vibration stops completely. Not sure what the relation is.