We have a GE electric 50 gal. hot water heater 3 or 4 years old. It did not heat well right from installation, just figured that was it (2nd shower would be running out of hot water). All of the sudden, a few months ago, it actually felt like HOT water, my husband turned the thermostat down. Was good for 4 plus showers and more. This lasted just a couple months and is now back to running out of hot water on 2nd shower. Husband checked both elements and they tested OK. What should we do next?

Is your complaint that you have lukewarm water or that the hot water runs out too soon?
How did hubby test the elements? Did he also test or replace the thermostats? If you're sure the elements and the water doesn't start hot and quickly turn cold I'd be giving a hard look at the thermostats . I'd replace them and see if that didn't solve the problem. Good luck, Tom