Some suggestions:
Dragonfire Adept (from Dragon Magic -- not on your sources-list, but about as weird as the Warlock, which is).
Max out your Constitution and your Use Magic Device skill, and avoid having a Cha penalty.
For your Invocations, take the one that makes your team mates immune to your breath weapon, and the one that lets you identify loot for free. Take Draconic Flight and Voidsense (fly all day and blindsight 30 ft. radius). Get these wands:
glitterdust,
silence, and
invisibility.
For your breath effects, choose Frost Breath and Slow Breath. At 10th level, choose Thunder Breath.
For at least two of your feats, take Draconic Auras (Senses, Stamina and Swiftness are all good choices). For your 12th level feat, take Double Draconic Aura.
You'll be like a Bard (auras buff allies), but you can actually lay down some arcane smack-fire every round.
Dragon Shaman (PHB-II) -- as Dragonfire Adept, but front-line melee, and no Invocations or Use Magic Device. You buff your allies via Auras, and you also blast away with your breath weapon. You can heal, too, which will take some heat off the Cleric guy.
Scout (Complete Adventurer) -- mobility fighter, can skirmish or do archery, and has a lot of skill points. Excellent trap-monkey.
Scout 1 / Cloistered Cleric 4 / Shadowbane Inquisitor 4 (Unearthed Arcana or SRD; Complete Adventurer) -- another skill monkey, but with a bunch of Cleric thrown in too. Two part-Clerics will serve your party better than one. And there's already a Paladin, so you won't be dragging anyone down.
... and the final build that will be TOO MUCH FUN to possibly resist:
Rogue 2 / Ranger 2 / Cloistered Cleric 1 / Chameleon 4 (Unearthed Arcana, Races of Destiny) -- You must be a Human to use this build, and take a specific feat from RoD at 1st level.
Why end your indecisiveness today? You can be indecisive
every day with this build!

Also, from a power perspective, your caster level will be 20 at level 16, so you'll be perfectly seated to end that module on a high note.
Cheers, -- N