Warrior tank help

[HeadAche]

I've been playing my warrior tank as an alt, now I'm switching him as my main and using him more in 25 mans. Basically I can't seem to hold aggro anymore
The World of Warcraft Armory

my rotation basically consists of; Sunder Armor/Devastate, thunder clap, shield slam, revenge and rage dumping with heroic strike. I'm up against a pally tank and a dk tank, obviously I don't plan on aoe tanking off them but on a single target boss I can't even hold it. Any suggestions? Macros? Addons?

[squats]

switching to the 15/5/51 spec will help out a lot
15/5/51

make sure your spamming the hell out of heroic strike. and dont use devisate unless nothing is up

get rid of those parry gems please.. they do nothing theres a dodge gem out there too. or you can go for expertise/stam

[clavarnway]

I've been playing my warrior tank as an alt, now I'm switching him as my main and using him more in 25 mans. Basically I can't seem to hold aggro anymore
The World of Warcraft Armory

my rotation basically consists of; Sunder Armor/Devastate, thunder clap, shield slam, revenge and rage dumping with heroic strike. I'm up against a pally tank and a dk tank, obviously I don't plan on aoe tanking off them but on a single target boss I can't even hold it. Any suggestions? Macros? Addons?

Your expertise is pretty low. You want to shoot for at least 26, since at that point you remove Dodge from the combat table. Before 26 Expertise, Expertise rating is 2x as good as hit rating, since it costs the same but removes Dodge AND Parry.