Hi all, I recently had the the entire clutch and pressure plate replaced in my car and ever since there has been a sound like metal rattling in gears 2-4. It happens when I have low revs in those gears (particularly going up hills) and seems to go away when I am at high revs (~3k+). The mechanic I initially used says it’s nothing but it sounds awful and is making me very nervous. The “Check Engine Soon” light has gone on as well.
Any help or advice would be greatly appreciated!