PT Cruiser 2008, weird clunking noise about over half time i accelerate.

Hi, i have a PT Cruiser 2008 four door hatch back, with only 97000 kms on it, I'm having this weird problem, about over half the time i accelerate i get the clunking noise from right under my feet, i checked the tie rod ends and the suspension, so i have no clue what it is, the noise just sounds a massive thud but it doesn't happen every time i accelerate its way over half the time, i have to start off really slow so it doesn't happen. I was wondering what it could be cause its driving me mad, thanks!