5.0 Sluggish & Pinging

[Thallarsen]

My '99 5.0 Limited is starting to ping under acceleration at higher speeds, and seems sluggish going up hills at highway speeds (minivans passing me for crying out loud).
I have new high performance wires (Taylor Spiro), and new plugs.
A while back, I replaced the differential air flow (EGR) valve after the CEL came on (no CEL since then) and cleaned the MAF at that time (didn't look too dirty).
The air filter isn't new, but doesn't look too bad;
I use regular major brand (Exxon, Shell, Mobil, etc). and I recently ran some decent injector cleaner in a tankful.
I can't complain about my mileage (still around 18 highway/around town); but the sluggishness & pinging seems to have worsened.
What should I check at this point?
125k w/no modifications.

Thanks,
J.P.

 

[jjue]

One thing to look at again would be the MAF meter, and I'd check to be sure that you clean it with carberator cleaner. I had a problem with mine getting dirty from the oil on my K&N filter, and throttle body cleaner didn't clean it to keep mine from leaning out. You can also unplug it to see if the computer will go into a default mode to see if it runs. I happened to have left mine uplugged when I was working on mine last week, and that's how I determined that my MAF meter was the culprit.

Another thing is that you said that you changed the plug wires, but did you change the plugs & check the gaps? Just for kicks, get another air filter since it definitely won't hurt. Also, be sure that you are getting the proper amount of fuel pressure, and if necessary change the fuel filter.