2000 malibu STUMBLE on start, need help

[wolfort]

1. cold start is very good in cold winter (0F), usually crank and start in 2-3 sec.
2. warm start is fine if the coolant temperature is between 160-200.
3. if the coolant temperature is below 150 or cold start at warm season (50-100), the engine hesitate to start.
the symptom is:
(1) one the first try, the engine cranks normal, but usually do not start after 5-8 sec crank.
(2) on the 2nd try, it usually starts after 5 sec crank, but the engine stumble when starting, the rpm begin at 200, then stumble to normal idle speed (~1400rpm)

it's not anti-theft system's problem;
the sparks and wire are tested to be good;
fuel pump & fuel filter are newly changed;
no check engine light;

find a similar TSB for 99 model:

TSB #020604009 -- SUBJECT REGARDING HESITATION OR STUMBLE ON THROTTLE APPLICATION AFTER COLD START (REPROGRAM PCM). *JG (NHTSA ID #629502, MARCH 01 2002)

TSB #151101 -- ONWERS MAY COMMENT ON A LIGHT HESITATION OR STUMBLE AFTER A COLD START AT TEMPERATURES BELOW APPROXIMATELY 50 DEGREEES FAHRENHEIT OR TEN DEGREES C. *TT (NHTSA ID #628134, NOVEMBER 15 2001)

Could anyone help me find the full version of these tsbs.
Thanks!

[wymi]

My 01 Malibu use to hesitate slightly right after start up. I found the motor to be very sensitive to the brand of gas we used. I switched to Shell regular and all hesitation after start up is completely gone. You should run some good injection cleaner like redline SI1. Probably wouldn't hurt to check the fuel pressure regulator, pull the vacuum line off and check for gas vapor, there should be none. Also, I found out the hard way that oem is the only way to go on plugs and wires.

[Negatoro]

Go grab Delco plugs and check fuel pressure.

Report back with results.

I believe malibuclub.ca has a huge sticky thread for malibu TSBs.
..might be unitedmalibus.com

-Mark T.

[timiii]

Hi,
I have a 1998 Oldsmobile Cutlass GLS and it is behaving exactly like this Malibu. Did anyone figure out what the problem was?

Thanks!