For owning my car for over 22 years now, I have also had this problem. I have done all the quick fixes, parking on hills, quick turn of the ignition before shutting off and rebuilds and or cleans. Rebuilds or cleans would last for about a little over a year then back to the same thing. I then rerouted wiring away front the stock manifold. Wiring was ok. Strange but I decided to take off the heat shield. That seemed to help a little where I didn't have as many episodes of not starting.
I bought a new starter.... (you're gonna like this) It sat in the back of my car for 3 years and then in storage for 3 more years until the new starter was trash due to condensation and calcium buildup. (horribly humid area I lived in) The new starter sat because all of a sudden my old one stopped having issues and for about 10 years, stuck with the same starter until this year when it just flat out died. I no longer have the stock manifold but changing a starter is still a pain. All is good now after going through 2 new starters and so far after 6 months, I have no problems.
So this was just more of a story to tell but you may try some of the things I did and see if it works if you're like me and money is not easy to come by in large amounts. hehe.