sts stalls need advice

01-11-2009, 10:19 PM
my 1993 sts with 4.6 northstar has aquired the rather annoying habit of stalling upon decelleration. i pulled the error code (p097 P/N to D/R at High Throttle Angle). can anybody tell me what causes this and/or what parts i will need to remedy it. thank you

01-15-2009, 06:02 PM
Hey you drive a Caddy, get it fixxed professionally.:loser:

01-15-2009, 07:21 PM
Hey you drive a Caddy, get it fixxed professionally.:loser:
Welcome to AF, this is not how we operate here, if you have no meaningful input then don't post anything, thanks.

01-15-2009, 07:22 PM
Welcome to AF, I would clean the throttle body and remove and clean the idle air control for starters. You may need a full scan to look at the tps and iac operation also.

09-29-2009, 10:21 AM
:banghead::sorry:oops sorry!

01-18-2010, 10:43 PM
Is it also throwing out an emission code? carbon-clogged EGRs are common in mid-late 90's STSs and SLSs, and they show up as emission codes, I forget which, but often times cleaning out that EGR can mean the difference between a perfect-running Seville and a junker (note that this is only if the EGR is actually the problem :-P)

01-18-2010, 10:58 PM
P079 = Park to neutral drive to reverse at high throttle angle, the idle speed is to high during shift.

Cleaning IAC , Air Mass meter, Throttle body, and EGR system.
New PCV valve + air filter

The stalling part sounds like no air, when the throttle plate is closed.

Because of age, do a smoke test for vaccum leaks.

Were you giving to much gas during the shifting into drive?

The Throttle position sensor could be bad, if no idle.

02-11-2010, 09:42 PM
Check the Idle Speed Control Actuator. It's located under the air intake tube right near the intake manifold connection. If it's not reading signals correctly it will cause erratic idling. I'm thinking that when you decelerate the ISCA is allowing the throttle linkage to retract too much causing a stall. I have personal experience replace one on my previously owned '94 Eldorado. This is just a suggestion.

Here's a pic.

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