MY 1998 blazer ran just fine yesterday, driving around in the snow in PA. i got in it this morning and it started up and sputtered and died. It has done it once before, the day after driving it around in heavy rain. This makes me think that it could be moisture related. If i can get it to crank over and fire, it will run fine for a minute or so, then die, or if i give it gas it will try to shut off. what could get wet and throw it that far outta wack? crank position sensor? camshaft position sensor? O2 sensor?

 

Is the SES light on? If so, have you retrieved the Diagnostic Trouble Codes, (DTC's)?

How many miles since you replaced the distributor cap, rotor, and spark plugs using AC Delco parts?

How many miles on the plug wires?

Have you checked fuel pressure and leakdown? Moisture will not affect it but it's a good idea to at least check it.
Here's a link: https://blazerforum.com/forum/showthread.php?t=45941

 

Check your fuel pressure, it could be your fuel pump going out.

 

Cap n rotor, plugs, and plug wires are probably 35k old. The ses light is on, and its from a cat efficency code. fuel pressure is good. Im going to replace the cap and rotor and check the distributor in the process... any other ideas?

 

35K is about normal for aftermarket caps. AC Delco is up around 100K... definitely worth the extra few bucks. Make sure you put a dab of silicone dielectric grease on each terminal, inside and out, of the cap. Probably a good idea to at least check, and adjust if necessary, camshaft retard. Spec is zero degrees, plus or minus 2 degrees. If cam retard is out of spec, it will shorten the life of the cap and possibly the drive gear on the distributor. It will not set a DTC unless it's off around 20 degrees or more.