03 Chevy 1500 loses all power

Question type: Maintenance & Repair

Okay so I have a 03 Chevy 1500. It has 5.3L
v8. I was driving down the road and went to
pass someone and gave about 3/4 throttle
and you just fell on its face. I took it to a
dealer to diagnosis it and they say 2 coils on
cylinders 4 and 6 were bad and needed
plugs and wires. I changed that and still
nothing changed so I took it to another
mechanic and he ran some more diagnostic
and its still throwing the same codes? Any
ideas? It has no power and spits and
spuders. I've also tried the fuel filter and
checked the pressure on the pump, no
problems there. Just want to know if there's
any thing I should check before I take it to a
dealer and waste a lot of money.