General Recipe Trouble Shooting

I just don't get it, I have made meringue to top lemon pies and tarts for years. If memory serves me, it will deflate and drip in a day or so. Lately it seems to happen sooner rather than later. I have tried adding cornstarch to the eggwhite, cream of tartar, sugar and vanilla mixture. The cornstarch did not help one bit.

Is it me? Or have eggs changed?