Swimming Issues

Hello Everyone,

I have a bit of a swimming dilemma. I have been training for a year now and I have three tris planned for this summer, (the 1st of which is 7/16). I have done a few open-water swims, but the vast majority of my training (95%) has been in the pool with no wetsuit. I recently started training with a friend of mine who has completed a handful of IronMans and is a total wealth of information.

When we do our OWS together, he always reminds me to slow down my stroke and swim in "slow motion". I definitely have experienced the benefits of slowing down and I realize that I can swim just as fast without expending so much energy than I do with my usual thrashing about.

My problem is not with the idea of swimming with slower, more purposeful strokes, nor is it that I am not comfortable in the open water...
This morning I swam 2500 yards IN THE POOL and tried very hard to focus on technique. I was going well for the first 800 yards or so, (going along at my usual 1:56-2:02/100yard average) all while swimming in "slow motion", but as I began to tire, it was back to my old ways.

I feel like the wet suit makes it easier to swim with longer strokes and I think I spend a lot of energy just trying to keep my legs and hips up in the water - and when I slow down my strokes, staying afloat becomes more difficult.

Am I making any sense here? Can anyone please share with me some ideas that will make me more efficient and help me slow down my strokes more comfortably?

Thanks