My Suburban has this really frustrating starting issue. It starts perfectly every morning and late at night, like it’s brand new, but in the afternoons it cranks for way too long before finally starting. It’s not related to how long it sits either; sitting overnight is fine, but sitting all day at school somehow makes it struggle. When it does have a hard start, it idles rough at first but then smooths out. Weirdly enough, if I drive it and shut it off, it starts up just fine afterward. The thing runs great once it’s going, but this problem is just so annoying because half the time it starts up great and the other half it just cranks way too long.
It also previously would start and stay at like 100-300 rpm before actually catching itself and running normally, strangely enough this almost completely stopped happening and now it just cranks for a while before starting up, and still not as good as in the mornings.
New spark plugs and ignition cables and I dont think its a fuel issue, atleast with pressure because as I said in the morning no priming neccesary just turn the key from off to crank and it turns right on.
Apologies if I missed any important information im not too sure how this forum works but I just couldnt find anything like my problem online.

 

I'm having very similar issue, doesn't appear to be pressure related,. did you find the solution?