99' 2.7L: Mystery Sputtering and Power Loss

Before I start, I just want to clear a few things up before you guys look at my lack of posts and make any assumptions, the basis of the answer to my problem may have been in the forum somewhere, but the goal of this post is to see if anyone else has had a similar experience to what I am dealing with right now, and possibly have some suggestions to solving my issue.

The Truck: 130,000 Miles, New O2 Sensors (Both), Recent Tune-Up (Plugs/Wires), New Fuel Filter, Cleaned/Checked MAF Sensor, Checked TPS... Basically I've checked the majority of the obvious sources of the issues. I had a CEL light before I replaced the O2's which I cleared. And Now the light is out and has been for about a week now.

The Issue: Where to start, The primary issue is a lack of power at lower rpms under load. 1/2 mile hills at 40mph which were not an issue in fourth gear at about 2k rpms, now require a down shift to keep sputtering to a minimum. And even in fourth gear at 40mph on flat ground, if I go to wide open throttle quickly, the motor sputters terribly, and if held for any length of time at WOT, it will back fire, and sometimes kick off a flashing CEL and when the motor smooths out after you get out of the pedal, the CEL will go out and no codes are stored. The Mystery to me is my ability to be able to go to WOT gradually with out issue. If the motor had a carburetor, I'd say the accelerator pump was junk... The motor also has a consistent intermittent skip. Every 10-15 secs at true low idle 750 rpm (AC/Heater Off with engine warm) the motor "gasps" and skips a beat and then as fast as it happens it smooths out.

I'm waiting for the CEL to come back on and have it read again, but until then, If anyone has any suggestions, I'd appreciate it. Thanks and if you need any other info/description of the issue let me know.

 

I would make sure the plug wires are "snapped" into each plug correctly and then check all the vacuum hose connections too.

 

Actually, when I changed the plugs they were gapped improperly, I regapped the new ones and the problem improved but not by much. And the wires are snapped completely in, but I admit I haven't spent enough time checking all of the vacuum lines, I will concentrate on that in the next couple days here and get back to you guys, thanks for the quick responses

 

Problem Solved, the CEL came on and I had It read, Mis-Fire on #4 cylinder. I said to myself "okay that explains it all"... Replaced the only tune up item I didn't touch... the wires, and the truck is running great.

 

In your original post you said you changed the plugs and the wires, I guess you just changed out the plugs. Just curious, where did you get your plugs from? How off was the gap?