I have good throttle response and acceleration as long as I keep my throttle input very conservative. If I add too much throttle (roughly anthing more than about 1/3 total available throttle)...........then the truck just bogs down and speed begins to fall off.

With light throttle, I can easily run up to 4500 rpm,.....under heavy throttle......I cant seem to get past about 3000 rpm.

I dont hear a vacuum leak anywhere.. Wondering if it might be a Throttle position sensor?

Truck start instantly and I am pretty sure that its hitting OK on all 8 cylinders....sounds and feels smooth.....its just not accepting anything more than moderate throttle.

BC

 

You check your spark plug wires? Be sure to check the coil pack. It's hard to see/get to, reach your hand back there and make sure none are lose, have fallen off. Something simple to rule out.


Also, you get any codes? If the TPS is acting up it should/will throw a code.

 

Its not missing, running smooth. New 8mm wires and platinum plugs. No backfiring on full throttle either, so think that rules out low fuel pressure.

 

Plugged catalytic converts will keep it from revving up, usually they get bad enough that even with light throttle it won't go over 2000 rpm.

Do you have any codes stored?

 

No codes,.....and it DOES rev to the 4500-5000 range with light throttle. Its only with more agressive throttle that it starts bogging.

 

Does it act the same even in neutral?

 

More or less,....in nuetral, with light throttle and I can run it up to 4000 or so,....I'm reluctant to go beyond that,......but if I just floor it in nuetral....it goes to about 3200, smootly, no missing of any kind,...and just hangs there. No hissing or whooshing out of the tailpipe that I have heard on other cars with a clogged converter.

 

So, I had these exact same symptoms in my Infiniti - yes I know different animal!

It threw no codes, and could not get it to rev with anything but feathered throttle. I diagnosted it by unplugging the MAF, and test drove it that way. It made no difference, so I changed it out. Worked a treat . . .

Just my new $.02 . . .

 

MAF sensor is actually a good call. Take it off and see if that makes a difference. It's easy to remove/replace if that's what it is. You could also try and clean it, if that's possible.

 

Not bein a wise guy at all,...just dont recognise the term "Worked a treat"...........is that Good?..........does that perhaps mean it fixed the problem?

BC