On the way in to work this morning went through two and a half feet of standing water. (wasn't the first time). Truck went through just fine stumbled a little and then ran like a top. Truck sat 12 hours at work and started it up just fine started driving and it was a dog would floor it and just would creep along. Motor revs fine in neutral put it in gear and its a dog.

truck is 05qc g56 w/ tst box

 

I would check the filters to make sure there is no water in them, and then I would see if water got in the fluids.

 

Check all the electrical connections especially the ones that are low and could have been submerged, one could have some water in it.

I would also check the differantials for water and grease any joint that has a grease fitting.

 

x2 on checking the filters, especially the the air filter.....no air= no go!!! 2.5 feet of water.....definitely check and make sure all elec. connections are dry and verify that diffs have no water in them.