I have a 1995 Tahoe, 5.7L V8. I recently did a tune-up on it (replaced wires and spark plugs). And now she's lacking power, everytime I press the gas pedal I dont get what i used too.... On the highway I have to floor it to get her going. I also adjusted the distributor because it was misfiring. Timing is ok recently checked. I dont know what it can be.