Car shut off in Park, common culprits?

[GMUE03]

Could be the EGR, but unless you know the TPS is good, it could be opening the egr because it thinks the TPS is in a cruise position. TPS controls a lot of stuff, so it's always good to make sure it's not bad first.

Ah ok. Didn’t know the TPS had its hand in that many pockets. The weather is crappy this weekend so next weekend I’ll pull the EGR off and clean it and also test the TPS.

Is the EGR valve supposed to be spring loaded closed? I do remember putting my smoke hose onto the little vacuum port on the side of the valve and I watched the diaphragm shoot forward. I thought that was weird that it would move under positive pressure.

[GMUE03]

Update: the weather cleared up slightly so I had some time to look into some things. I removed the EGR valve and inspected it for cleanliness/functionality. While there was some carbon buildup, I don’t think there was enough to cause the pin to get hung up (see image). I put negative pressure on the vacuum port (in a old fashioned way) and verified that the diaphragm moves the pin and returns it to the close position with a strong spring force…ok…so not a valve issue it seems.

Next I went over to the control solenoid and popped the cover off. I didn’t see anything obvious but someone on a foxbody forum said that occasionally these can seize up, so I gave it a quick blast of silicone lube. The foam filter disintegrated as I went to remove it so I cut some new foam and stuck it in there.

After all this I fired up the car and let it idle for about 5 minutes, then went from Drive/reverse to park about 10 times with no issue. No stumble or anything.

So I think that this is an intermittent issue with the aforementioned TPS or the IAC, just my theory.

As far the the 34 code goes I think it might be a red herring…

I’m gonna do some research on testing the TPS. It looks like you just need to back-probe it with a multimeter.

I will keep this updated. Thanks for the help so far!

[sly]

If the EVR solenoid was sticking, it could cause the EGR to hang open, so if the car doesn't act up any more, the shot of lube may have sorted it.

[GMUE03]

If the EVR solenoid was sticking, it could cause the EGR to hang open, so if the car doesn't act up any more, the shot of lube may have sorted it.

Fingers crossed Sly. I have a TPS in my cart on Rock Auto just in case..

Just some food for thought. Would disconnecting the battery cause the car to “relearn” some functions like the newer cars would? Reason I ask is because this started happening after I had the battery disconnected while replacing the window gears. I wonder if I didn’t do proper drive cycle and confused the EEC..

[sly]

Yes, it would relearn, but unless the idle is mechanically set too low, with the throttle stop screw allowing the throttle valve to close too far making base idle way too low, it shouldn't ever get close to dying as the IAC will open plenty to keep it running even if it's set a little too low. I doubt that is the issue since it dies when you remove load (put it in park) since this problem would be when in drive.

[GMUE03]

This just popped into my head, maybe it’s relevant here. When I did my KOEO test I didn’t get the 11/111 code. All it got was the 34 code, 10 (continuous memory), then 34 and that was it.

Edit: this is irrelevant. The lack of a 11/111 code means that there was a stored code. (I’m new to OBD1 lol)

[gadget73]

34 is sometimes an EGR position sensor problem, but it can be a nugget of crap under the valve preventing it from closing, or a bad EVR causing the valve to get vacuum when it should not. Since you've verified the valve is OK, unhook the vacuum line from it and see if anything changes.

[GMUE03]

34 is sometimes an EGR position sensor problem, but it can be a nugget of crap under the valve preventing it from closing, or a bad EVR causing the valve to get vacuum when it should not. Since you've verified the valve is OK, unhook the vacuum line from it and see if anything changes.

I did try this. The line going to the valve had no vacuum on it, however I did this while the car was idling normally and not loping.
Along with testing the TPS, I plan on doing a KOER test to see if that yields anything.