This has just recently started happening with my 98 blazer. I tried starting fluid to no avail, other than using up a bottle of starting fluid; then just waited about 20 minutes and it ran like normal.
The 'service engine soon' light came on and I had it checked at autozone.
The codes P0101 (mass air flow problem) and P0108 (MAP sensor and barometric sensor) registered. Unfortunately 2 seperate diagnostics couldn't tell me which to replace. Someone here recommended replacing the fuel filter which I plan on doing tomorrow; but I wonder if that is the problem since the blazer will eventually start and run just fine.