96 4.3 l throttle problem

I have a strange problem when im driving on the highway and i let off the throttle it takes 20 seconds before the rpm will start dropping.
It seems to be getting worse. There is no service engine light.
O and its a 5 speed manual transmition . In neutral the throttle respond norm.
this problem only happens when moving.
Could it be the vehicle speed sensor??
:screwy:

Welcome to AF.
What rpm range does it stick and does it hold rpm with clutch pedal down or up?

Have you checked the TB for carbon build up?
Does the computer control the idle when stopped?

It seems to stick at at about 1500 rpm whith the cluctch in or out
only when the vehicle is moving. realy strange. I took it to the Chevy dealer
they said there is a problem but thay couldnt fix it because they didnt
know wat it was. So much for dealers lol.

Check butterfly for carbon and IAC valve.
If going to a delaer.

Tip on going to the dealer
Ask that only a factory certified gasoline engine performance specialist work on your car.
Not all dealerships are concerned with how repairs are dispatched, and not all dealership techs bother to take advantage of the training offered by factory (the vast majority of which is paid training). If the dealer is uncooperative, ask for your money back and call around for a dealer that will accommodate you.

Thanks for the help ill give it a shot. thats alot cheeper than the $150 i spent
whith the dealer. ill post back whith the resolts.runaround

A old tooth brush and a can of carb cleaner or a can of throttle body cleaner on the butterflies works good.
And if real dirty remove IAC valve and give it a couple shots of cleaner.
Good Luck
MT

Ok I took the throtle body off and claend it took the aic off and cleaned
it and it port but still have the same problem it doesnt make sense.
withe the truck stoped and in nutrol it will throtle up and down whith no
problem. It only does this when the truck is moving. Even does this when
the truck is moving and in nutrol. just woent idle down but when i come to a stop it will idle down GRRRRR. Any other suggestions would be greatly helpfull
Thancks in advance

:banghead::banghead::banghead::banghead::banghead: :banghead::banghead::banghead::banghead:

Your next step is to get on a good engine capable scanner and check IAC valve operation and what the computer is comanding/telling the IAC valve to do.

Ok ill do that but first let me through a curve ball in to this.
My Registration is due and i had to have it sog tested today.
I live in California so you know its a tuff test to pass.
The darn thang passed whith flying colors. the guy at the smog shop said
all sensors were reading fine and emitions where great. Think ill just buy
a new aic valve its only about $50. The valve looked prity nasty whin i took
it out and didnt move in and out very easy i figured out that ita a servo valve
thancks agian I was so lost till i found this board. Ill recomend this site to many other 'DO IT YOUR SELF' Machanics .
:screwy: