Can't tell really by the connector photo but it could be a solenoid connector on the transmission. If it's solenoid number 1 you are stuck in 3rd gear that's why it's hard to accelerate.
Here's a link to the manual of the transmission
http://www.---------.com/camry/ax2.pdf
Go to page 98-103 and diagnose your problem.
it's turbo ninjas .com in one word(no spaces) for some reason i can't post link but it works type it up. Copy the link and write it instead of the ------'s
ALSO IF YOU PUT THE TRANS IN L mode you should be in first gear. In D and 2 you will start in 3rd