possible MPFI swap ?

[Dharmabum]

I picked up a very clean 98 suburban with 127k miles on the 5.7 last week. It runs great, smooth on the highway, not a ton of power but what I would expect of a small block in a heavy truck, etc.. but does have a starting problem at certain times. If it has been running and I stop to run in a store or something (about 20-30 minutes) it will have to crank a little longer to start up, feels like its flooded, runs rough for a few seconds. If I restart it right away (under a few minutes) its fine and if it sits for a long time like overnight or while I'm at work its fine too. My thoughts are a leaking injector or I guess it would be a poppet that is flooding it but it evaporates if it sits for a long time? I have done some reading on a lot of different issues with the spider injection system and the MPFI retrofit/upgrade and it seems like it would be a good upgrade for me and probably fix my issue. Does this sound correct or is there something else I should check out first? I don't seem to have any drivability issues but would rather take care of the problem before it gets worse.