Alright, I'm completely stumped, I seriously am out of ideas of what to do anymore. As stated in a previous thread I've been having this horrible hesitation upon acceleration, and once i get up to high rpm's prob around 28 to 3000 it goes away but I need to shift before then! So anyways, upon a lot of info from a bunch of helpful people I bit the bullet and started throwing parts at it hoping for some sort of response, and nothing!!

Here's a list of everything I've replaced so far!

Fuel Pump
Fuel Filter
Fuel Pressure Regulator
O2 Sensor
Spark Plugs
Spark Plug Wires
Distributor
Ignition Coil
Idle Air Control Valve

Now, having said that, I've looked into the egr and when I unplug it while running it definitely makes a difference so I assume that it works. I tried plugging the vac line that goes to it and got no difference. I've cleaned out the throttle bodies too, they were gummy but nothing too major. And I was told to check the computer out so I did. And when I pulled it, it was a remanufactured one already, checked everything inside and it all seems fine nothing was broken or loose or anything so should I assume it's okay? I'm running out of money to throw at it hoping it's going to work so with all the info I've given hopefully some of you guys can see something I'm not seeing or noticing! Thanks for the help so far it's been great!

 

Have you pulled the codes?

 

I'm only bringing up system pass code (111) now that I put the new O2 sensor in.

 

How about throttle position sensor?

Bad fuel

Vacuum line (to test vacuum line get a can of carb cleaner and while running slowly and lightly spary carb cleaner around vacuum lines)

Have you looked at the possibility that the cat is clogged?

 

I was thinking about the tps. It was replaced two years ago though, hoping it wasn't bad again. I just put a brand new tank of premium in with injector cleaner yesterday. Also the truck has no cat, didn't have one when I bought it was all straight piped but I put two glass packs on it. Can I use anything else around the vac lines to check? Just cuz I don't feel like running across town again haha. And I forgot to mention it takes 2 to 3 times of trying to turn it over before it will fire up.

 

I went out and tested the TPS for voltage with my multimeter. I have a steady increase in voltage as throttle is pressed and steady decrease as let off. About 1.09V to 4.66V is my margin when accelerating. So according to the internet, if it has that steady increase and decrease it should be good.

 

Have you checked compression?

 

Also ive heard of people using wd40, soapy water, all kinds of things but carb cleaner is what I prefer

 

No.... whats a good compression range? Ill go get a tester.

 

100-150, of course the higher the better. Also all cylinders should be within 20% of each other

 

My 95 4.9 had a vacuum line broken right behind the block, at the head level, by the firewall.
It's the black one that feeds the EGR sensors.. Truck would skip, and jump bad between gears.Buck so bad I hated to drive the truck. Drove me crazy, never threw codes. I found it one day by accedent.
You may have to use a mirror to look back there. I figure it probably got pinched when the clutch was replaced.

Truck runs like new now that it's fixed

 

Thanks Dusty, as the EGR seems to be such a pain in these trucks I'll go out and take a look after this here.

Also, I did the compression test:

Cyl 1: 150 psi
Cyl 2: 150psi
Cyl 3: 150psi
Cyl 4: 152psi
Cyl 5: 150 psi
Cyl 6: 149 psi

This seems pretty damn good for having so many KM's. I thought I'd better try it again and I got the same thing doing it a 2nd time!

 

Thats damn good there buddy

 

I checked those vac lines behind the top of the motor that feed the EGR. They seem to not be leaking I sprayed soapy water all over them with no bubbles. Any other ideas?

 

Ok heres what you can try, fire the truck up and let it run five minutes then cut it off, then pull each spark plug one by one and see if any of them are wet. If they are one of two things are happening, either your plug is not firing or you have a bad injector.