Bed cover and uneven rear suspention

After begging toyota to sell me an oem bed cover,I spent another week on deciding which one to buy.I chose the Extang Encore as I think it looks like the oem,900 bucks-owch.It looks great and I'm glad I spent the money.I'll try to get pics,it started raining as soon as I flipped the lids.While looking at it from behind,I noticed the truck sat lower on the drivers side,took out my tape measure and found it was an inch and 1\4 lower,the spring is straight.Should a full tank of gas have that effect? I don't think so.I guess it's time to go to the dealer and complain.Sometimes the trans,from first to second is slow.At 750 miles,I'm only getting 20.8 mpg at 75% highway.I hope the cover helps. Dan

 

Tacoma lean, normal and common. due to gas, battery, drivers controls all on one side. 1 1/4"? same as me.

 

Its normal. Its the Taco lean.

Mine is about 1/2 - 3/4. Its a lovely sight.