5x Shaman WOTLK Heroics? Yeah, get a tank. WOTLK Normal modes? No problem! You should be able to handle most without any problems, I can tell you that gear is also a complete no issue as I had CRAP at the time (you could argue that I still have crap). I leveled up basically just running instances... doing UK (70-72)/Nexus(72-74)/Ahn'Kat(74-75)/Gundrak(75-78)/Halls of Stone(78-80). Now granted, some of the final bosses I wasn't able to kill at the time which is fine as you can just reset the instance and re-run for more XP and most of the bosses were very easy and killable....clearing trash was always pretty fast too....gundrak and UK were phat xp per hour.

So, If you are wiping on trash my first question would be how are you handling the pulls? For big pulls just open up with all your stoneclaws down (not always needed TBH) and drop a nova so it hits just after the melee reaches you...then start your thunderstorm rotation (I like to have an earthbind down as well so the mobs are all snared when they walk back). If your doing it right, your avoiding pretty much all incoming damage...the faster you can do damage, the fewer cooldowns you can get by using

Actually have a video here FWIW of me doing some UK trash and some bosses back when I was level 70-72, no editing or anything (heck, didnt even edit out some vent chatter....lol) ....its just a quicky and dirty video capture I did to show some of my buddies how silly shaman are

http://www.youtube.com/watch?v=0XyGs2HW_wA

hth