1998 gmc 1500 4.3liter

You say it wants to start? and you went threw the trouble of just changing the fuel regulator? The 4.3L Vortec motor is notorious for problems with the injector assembly, until it is changed out as an assembly unit. First any way, you had the Ignition Control Module checked? Also should look at the distributor cap on the inside, outside for burn marks. If your not finding a problem with that, then a fuel pressure bleed down test would be in order. You hook up a fuel pressure gauge to the Schrader valve on the intake manifold, build up fuel pressure, which should be 56 to 63 lbs, and with the key off watch the fuel pressure gauge. It should not drop more than 5 lbs in 3 minutes. If it does, then there is still a problem with the injector assembly.

Yes starts then dies right off everytime gna check fuel pressure today jus dnt no wat else I could b missing

Ignition module checked fine the other day may check it again today though

Waiting on results.

Im having the same problem with my 02 Chevy Silverado 1500 hd with the 6.0 ive done everything u said and some and i stil cant figure it out