91 s10 blazer engine surges warm and cold, stalls

WHAT COUNTY???????????????????????????????????
hot engine, cold or both?/// a key question
WHAT ENGINE: ( usa list , ONLY)
2.2 L F22B I4
2.2 L F22B6 I4
2.3 L F23A I4 2.3 L F23A7 I4
the fsm covers this. hose thing.... all hose can be followed,
unless its axle vents on 4wd cars. (they go no where, special)
is surging the only symtom.?
no engine stalls.?
lack of power in any gear or hills.
no misfiring?
no flooding.?
starts easy/?

ok what is surge, that it really is idle controls bad or out of comtrol
1: idle controls bad. (isc dead?)
2: or engine is running way too lean, and ISC cant keep a grip on idle.

easy huh?
and #3 misfiring so bad the idle controls fail.
are all fuses good?
is the CEL lamp glowing , then goes out running engine.
no , the scan it. or do the flash DTC codes trick.

a good tech ,first finds out if the engine holds closed loop status
hot. at idle, if not, he fixes that first.
as he/she knows that idle is the last thing to work right, in EFI.

one other way to get surge is air leaks (aka. vacuum leaks)
if the engine (unsaid option) is MAP based, it will race fast
with any vacuum leak, and it dont take much of a leak
to make the ISC idle controller go nuts.

so repost , hot/cold both questions
and actual RPM numbers. we need numbers
is the dash Tachometer missing. ????
and what engines in car.

all lean engines surge.
all ISC systems can surge if out of control , not all do this. just 1/2
if the ISC surges, it means its trying hard to gain back control.
this is called a software servo loop.
The ECU is programmed to hold rpm near say 800 RPM hot.
and is very digressive in that role.
I have a 91 car that will surge, with any vacuum leaks.
(by design) depends on which engine.

Engine stalls cold or RPM fluctuates at idle up and down or dies near idle.

This problem is commonly caused by a dirty automatic idle speed control valve and throttle valve but always run a OBD2 fault code as well as the cleaning procedure. Buy a can of throttle valve cleaner (do not use carburetor spray cleaner!) from NAPA or Carquest (made by CRC chemicals) and spray it into the air intake while the engine is running, use up about 1/2 the can, engine will try to stall hold the speed up, shut it down and let it soak for 30 minutes, restart and blow out the remaining fluid, shut it down and disconnect the negative battery cable for 5 Min's to reset the base idle control. If the above cleaning doesn't cure your issues you need to have the computer controlled automatic idle speed control system diagnosed and repaired by a dealer or electronic engine control repair shop.

I Have a couple of questions. First question does engine surge when idleing cold? 2. Does engine start quickly without a lot of cranking, Cold or warm? 3. Do you have funny smell at highway speed, or after you stop? With out this info and your imput, I would only be guessing. I am retired mechanic of 25 years. and would like to help if u need me.

This is called idle surge, do the following to correct it 90% of the time. Read the many symptoms and then do the procedure exactly as outlined by nme in the article I wrote about this.

Here are the common cause of idle surge, cold stalls, stalls at stops, slow idle speed, erratic idle speed, rough idle and engine hesitation (and other problems), it is in most cases the idle speed control air-bypass valve and or throttle valve and upper intake, these area's get full of gunk and combustion residue over the miles and cause idle issues (stalls, low idle) like yours.

To correct this problem I want you to get a can of intake cleaner (ABOUT $5.00) from any local auto parts store like NAPA or Carquest, do not use carburetor spray, intake cleaner only or u will damage the Teflon coating inside the throttle valve and air bypass valve, it is made by a company called CRC, remove the air intake hose to the engine, hold the idle high so the engine won