new to the board and need lots of help

[neversatisfied]

I have had my 2002 ml 320 for 2 years and I have noticed a few problems that i would like to fix, so please help me get an idea before i walk in a repair place and get hosed.

First my Gas gauge moves around alot, It will show i need gas(when that yellow light pops on) then i will either be driving and it will shoot up to half full, but 5mins later will go right back down to the yellow line. what could that be from?

second since i live in nyc and we have pot holes all over the streets when i hit a pot hole the truck sounds like its bottoming out, i changed all the shocks but the problem is still there. would really love to change this so i can have a smooth ride when i drive, what could this be from?

third is sometimes when i press on the gas the truck will take off other times it seems like its fighting for power and will struggle to take off, any suggestions?

Thank you for your help!!! i look forward to hearing from everyone