We put a lot of miles on our cars and I hate paying someone else to fix them....well wifee poos car had a intermitn problem...just sudenly losses pick up. sometimes when cold..others when hot....highway speed and city speed....would last a few min then be fine. Welp pulled ever sensor, electronic control module I could and hand them tested...no luck...pulled engin computer codes..none....changed fule filter, air filter, plugs cap roter....no luck...took it to the shop $35 not bad....Coil termanal corroded (Coil cost $13).... Lesson 1 keep it simple..check the obious. Put the coil on...decided to put new plug wires on....after being up all night....no loss of power...but now missing....check everything cuss scream...wimper.....now up 24 hours and getting grumpy...screw it took a nap....went out and looked....I put the # 1 wire on cylinder 3 and #3 on cylinder 1 (6 cylender engin). Lesson 2....dont rush..dont try to think when exuseted....and some times takeing a break from the problem and the problem will make some more sense. Now if I can just get that 454 engin to fit in my Hyundi Excell Ill solve its power problem.