I'm the proud new owner of a 97 ext cab XLT. 5 speed, 3.0. 136K
It starts and idles fine, although warm starts sometimes take a second crank.
Under load it is dog slowand develops a substantial vibration across the rpm spectrum.
i suspect i'm running on 5 cylinders.
haven't torn into anything yet. first thing i plan to do is pull the plugs and see what they look like.
from what i've read here so far, plugs/wires/coils packs seem to be a common problem.
talking to the previous owner, i don't recall him mentioning anything about ignition parts ever being replaced. the plug wires are not original (carquest). hard to say how old they are. plan on replacing them with motorcraft/autolite. will probably do the same w/plugs.
if i do have a spark issue, what is the best way to diagnose it? is it OK to lift a wire off the coil pack with it running, for a short time to check for rpm changes? or should i shut off the engine, pull the plug, ground it, then start it?
i suppose an inductive timing light would be handy. too bad i tossed mine years ago thinking they were obsolete.
as for injectors, i know that running cleaner may/may not help. can they be removed and cleaned? is it worth it? can i run it with an injector pulled to see how it fires or is that a good way to get blowed up?
would it be money well spent to just take it to my local mechanic, who i trust and have him run diagnostics on it? will he, with all his computerized gizmos be able to diagnose things I can't?