Within the past few weeks Ive noticed a lack in performance from my truck. It's a 99 with the 4.6. It's not a misfire or anything of that nature, just feels weaker lately.

Within the past 15k miles, the following have been done:

Changed plugs
Changed wires
Changed DPFE sensor (thanks to my P0401 friend)
Changed EGR valve (for no apparent reason)
Pulled TB and Elbow and thoroughly cleaned both.
Removed intake silencer and did airbox mod
Installed K&N drop-in filter
Changed fuel filter

Is there anything else similar to what I've done that will help wake my truck up? I know there's various aftermarket parts such as tuners and intakes that will add more horsepower, but I'm just trying to re-gain my old horsepower. Thanks in advance.

 

Not too sure if it'd regain performance persay, but you could try cleaning the MAF as well.

Also, you could check to see if your cats are clogged

 

yup , coud be those cats. i have 130k on my 97 and im waiting for them to go anytime. thats ok magnaflow high flows and muffler are going on.

 

Ive cleaned my MAF as well, sorry forgot to include that. I guess it could be the cats going, Ive noticed my exhaust sounds/smells different lately.

 

have u had the injectors flushed? u could also try that. my trucks been runnin like crap with a random miss. im thinking bad fuel causing the plugs to gum up. and miss randomly.

 

Hrmm is that something I could do myself or does it have to be done at a shop?

 

You can try fuel injector cleaner in the gas - I prefer Techron but Seafoam works too.

I believe the going rate to have a shop hook it up to a machine to do it is about 65 bucks.

 

yeh 65 is the going rate. should be cheaper if u bring ur own cleaner. like B12 or something

 

Ehh ive done the fuel additives in the past, never really had any luck. I have made another observation tonight though. When Im cruising around 40mph or so, at about 1500 rpms, if I let go of the gas pedal the rpm's drop down to roughly 700 then bounce back up and you can feel a slight lurch in the truck's movement. Also, when it's in gear and im idling, if I just slightly give it some gas and let off, like to inch a trailer back or something, the rpms will drop wayyyy low and the truck shakes like it's gonna die. What's goin on here fellas?

 

As far as performance - If you don't have a CAI intake and it being warmer , you sucking warmer air - That will decrease your performance.

The other probs , I would clean the TB and elbow + ports out good - Do everything by hand , it's easy to do..

While the TB is off the engine, clean the IAC - work the mechanicals inside after cleaning with Seafoam by hand (use the seafoam as a solvent to help break away carbon deposits) . Yeah after cleaning , just use WD40 and work the mechanicals as said . You can use a small pair of needle nose pliers, hemostats or a screwdriver.

Compressed air really helps allot when cleaning and will help force the lubricant in the tight spots..

 

Done all this but thanks for the tips I usually do my IAC every oil change, or every other oil change.

 

How many miles are on your truck? I'd try running a can of Seafoam through it and doing something about those pesky kitties... I gained 2 mpg and a ton of power when I gutted mine with 115K on them...

 

I had a very similar problem just a few weeks back, and I changed the fuel filter on my truck, and the problems went away, could be a bad filter, try that out also.

 

So what about the cold air intake ? Are you converting cooler outside air or sh^t air to make some ponies..?? - If I run an open box in the summer , I notice a decrease in power . In the winter it doesn't effect it much of course - but when it's about 80 degrees outside like it has been - I have to run a CAI..

 

Zaairman- Ive been thinkin seriously about gutting my cats. I just need to find out how the emissions tests go around here. Also, what's the average price on having this done? I know the cats are in a tight spot and shops around here are picky picky. I have 109k on the truck right now btw..

Erik- I think I'm going to try to change my fuel filter today. I did it when I first got my truck, roughly 30k ago. And since then I've put seafoam in the tank etc...which probably got all the gunk in the filter everywhere that it shouldnt be.

Jbrew- I'm not actually running a CAI just the airbox mod. I had a feeling it would hurt my performance a little during the summer but I never imagined it'd be this bad. Unfortunately I did the airbox mod that isn't reversable so now I either have to buy a factory airbox assembly or Fab-up a heat shield like one guy did out of a bucket.

Thanks for all the help guys