1998 Chevrolet 5.7 Vortec Problems.

Have you done any testing? Engine cranking, you have spark at the plugs and fuel injector pulse? Use a gage and check proper fuel pressure, key on engine off, 60--66 psi. The spider fuel system is noted for problems.
Any applicable trouble codes?

Yes they bolt right in.

the cap should be marked on a vortec 4.3 liter. the left side of engine is from front #1 #3 and #5 cylinders. the right side from front is #2 #4 and #6.

Check all connections and fuses/relays to see if you have a power liss . If possible check for power as close to the pump first .

If you have that spider fuel system, that system is noted for problems. I'd use a gage and check proper fuel pressure. Also, the poppet valves can stick.

I have a 1998 K2500 w/ a 5.7 Vortec. I hope you find this useful.-JW

You have to stay with an older model 4L80e. Your computer won't communicate with your tranny and your check engine light will come on.

there is no esc wire on a vortec. the distributor is set to zero degrees. if the check engine light stays on then adjust the distributor, clear the code, and try again. once the light will stay off it should be set right.

Shakes how? While stopping? Or solely while idle, Engine light on?

If if shakes while stopping you need to check you're wheel hubs and or Suspension ,

Shakes at a light, You may have a bad fuel Injector, Check you're psi in you're fuel pump, A TPS would cause low idle or sometimes high idle, With low idle and a bad motor mount it would shake,

I know theres a few things I'm missing but,.. I have a major Headache atm so I'll get back to you with some more, when i can think better. :)

sounds like your engine immobiliser fuel cut off is activating.try taking battery teminals off,re-connect and re activate your immobiliser fob the usual way,**** it will re-set itself,& or your fob battery may need changing,it,s anti-theft cut off that is your problem.good luck.