problem with my 96

Hey i have a 96 2 door with 4.0 v6 and 4wd (if this matters). anyways, a while back i started my car, then almost immediately the rpms just dropped and it stalled.. ok no big deal i guess so i started it again and same thing happened. i had to keep my foot on the gas to keep it running. I messed with it and didnt really do anything productive (except maybe make a better vacuum connection?) and it stopped giving me problems for the most part.
the biggest thing i noticed is that lately it seems like my motor has to work extra-hard when it shouldnt. for example, accelerating at just the speed of traffic around me takes a good 3000-3500 rms when it seemed like it used to take more like 2200-2500. the stalling thing happened a couple times since then but when i started it back up it was fine.

if this matters, the first time it stalled the check engine light came on and when i had it checked it said PO420 --catalyst levels below efficiency.. or something like that.. i figured the cat was plugged or somethin but i had it looked at and it was clean. since i had the light cleared the light hasnt come back on. any suggestions at all would help.. thanks

look at the sensor values with your scanner. look at the idle valve and the tps sensor. that low efficiency code is because it is sensing that your cat is not working efficiently. you will need a cat. this should not cause your engine to stumble and stall. have you done all the routine maintenace to the vehicle?

1) Replace or clean the iac valve.

2)You're going to need some trans. work.
You can prolong the life of existing trans
by watching the tach, and when you see
the r.p.m. start to increase abnormally,
let your foot off the gas a little, giggle the accelerator, and wait for
the gears to engage. Do not let the the truck
slam into gear. This is a common problem
with thiis truck.

ok thanks.. yes busa ive done most of the routine maintenance.. im gonna put soem new plugs and wires, and probably a fuel filter in it because ive had it for about a year and i figure this is all probably due.. otherwise, air filter, oil, trans fluid, coolant, etc have been maintained.. i might also pick up some injector cleaner and see if that helps the performance any.. if nto at least itll clean it out a little..

saperich whats the iac valve? i know i fair amount about cars but not enough.. just if you could describe where it is/what it does or anythign that would help me

haha i had been doing exactly what you said ... ill try to keep it easy on my trans and keep it shifting at about 2000 or 2500 like i have been lately. i treat it pretty well so im hoping i can get the trans to last as long as possible.. how extensive do you think the work will be? also how long do you think before my trans takes a dump?

The Idle Air Control valve is that shiney cylendrical object under the central engine cover
(where the carburator used to be).
It can be removed, and cleaned. A new one
is about $60 at Nappa.

The inherant problem with the transmisssion
is a poorly designed valve body. It's passages
get cloged with sluge . Flushing will not help.
...What actually ruins the transmissions is
the delayed shift, caused by the bad valve body
allows the clutches (in the transmisssion) to
engage at a higher rpm, and burn out.
....I have found that by accelerating a little
harder off the line (in first) the trans will
skip over second(the problem gear), and
go directly into third.

A new valve body installed will be about a grand.
(that may not be all that is wrong).
A new trans is about $2500 at AAMCO

I have been keeping my xlt running for about
30000 miles by useing the techiniques that
I have described.

And try not to let people other then yourself
drive the truck.

my moms 2000 xlt is having that idle problem, the check engine light isnt on, but when we first start it we have to hold the gas down to get it to run, or it dies, it is smoking too blue smoke, and the gas mileage has dropped big time.

yeah my gas mileage also dropped significantly.. before i was getting a good 15-18 like i should.. and now im at like 12-14 if that.. is this also a direct result of the trans problem? and ill clean my iac valve this weekend thanks

it sounds as if some of your fuel injectors are stuck open. check your fuel pressure. also tap on the injectors. most of the time is frees them up.

You are only getting 14mpg?
I was upset the other day when I checked my mileage and it was 23mpg.
I used to get over 26, but now it's got some miles on it (135K).

I guess that's one of the bennies of having a 5 speed.