I was the one who had the 98' Pontiac Sunfire that was making insane grinding and squelching noises on startup. Brought it in and it was a failing Water Pump... a six hour job that ended up being around $700 at the mechanic.
After I got it back it had a real bad idle (started after their work). They chocked it up to a totally unrelated 'issue' with leaking oil fouling the plugs and causing it to misfire. Well I put in brand new platinum plugs and it still idled bad right off the bad (obviously not enough time from the small oil leak with the valve cover/gasket to get in and foul the plugs). I had brought it back into them and they chocked this up to the oil/plugs and not anything they could've done with the new waterpump they put in.
The idle is like this: when at stop and in drive or park, the engine will sound fine and then kind of chug and cause the car to vibrate pretty bad, and then it will right itself up again and just circle the pattern. It's a very distinct succession... it will chug for three seconds or so and then right itself... rinse and repeat. Actual driving and performance seems relatively unaffected to me
Some good mechanic friends of mine (who helped me replace the plugs and check out that situation) said that something is definitely off, and it's not oil fouling the plugs. They said the way it sounds and acts that timing is off.
So my question: when they replaced the water pump would it had been possible to mess up the timing while they were at it? Obviously if that is the case they are not owning up to the responsibility so I need some knowledgeable outside opinions. Thanks for your help anyone.