A similar thing is happening to my client's site:
klekfm.org. I've tried that .htaccess snippet as well as increasing the memory. I've even read an article on here about seeing if it was a plugin causing it. I deactivated plugins and tested and still got timeout errors. I've tried every solution I can think of and looked up. I've even tried another plugin that's suppose to "fix" the issue and that didn't work (
Divi Tweeker). What do you do if plugins aren't "causing" the issue?
P.S., a unique issue with me is that when the page/post DOES work, I can mess with the modules.