I was performing well from past 3years.but suddenly got assigned other project and they put me into PIP.i am worried now.please suggest.

Most of the cases, this was a planned PIP your manager didn’t have balls or valid reason to put you on pip Hence changed your project

My advice, look out for opportunities and move on

Golden rule - PIP is a paid notice period by the company.

Sorry to hear, but u should start a job hunt aggressively.