Need some suggestions/help. My dad'* Bonneville runs okay at idle and with a little bit on the throttle. It coughs and sputters when I try WOT. A friend at work suggested that I replace the sparkplugs. I picked up some at Walmat, but I'm wondering how hard is it to get to the plugs on the back of the engine? How long should I wait for the engine to cool before I try removing the plugs?

Is there something else I should consider before I try replacing the plugs? I've already tried running one bottle of Chevron Techron injector cleaner through it...

Any help would be greatly appreciated.

Thanks...

Most problems like yours (over 90%) are not fuel related. Look at the ignition. This is assuming the fuel filter isn't over 5 years old.

Pull the plugs and inspect them. Do they all look the same? If not, replace them. Go out at night with the lights off, and turn on the car. Do you see sparking/arcing from any of the wires?

The ultimate fix in my book would be plugs and wires. Especially if the wires are original or have 40-50k miles on them. It could still be a coil, but of the 90% of these problems that are ignition related, plugs and wires fix 75% of them.

High speed engine problems like that can be those ignition components most of the time. And i recommend doing plugs at least, and then wires.

For ***** and giggles, kick your catalytic converter. A clogged cat will cause many problems @ wot, and is #2 in my book for this kind of problem. However hitting it is a free diagnosis...

I got the plugs and wires replaced over the weekend. The old plugs didn't look too bad, but one of the wires was all corroded. It runs like a champ now!

I have noticed when I rev the engine while it'* in park; it will go to about 4000 rpm'* and then fall off. I can hold the gas pedal down and it will keep going to 4000 and falling off. Is this a safety feature of the ECM to prevent the engine from over-revving while in park?

Yes it is.