'99 - Stuttering - Tranny? Manifold? EGR? Fuel pump??
 

Thanks in advance for your advice - I'll first say that despite my newbitude, I *did* use search, and didn't find anything that specifically addressed my concern. I'm kind of knowledgable for an average gal, but I only know about things that have been broken on my car before. :)

Here's the story of my car's issues:
Background, it's a base model '99, 134k-ish miles, 3800.

A few weeks ago, the car started running very oddly - It started acting like it wanted to shift when no shifting would be necessary, going on an even keel on a flat road... The CEL came on, and I stopped at Auto Zone (which was thankfully in view when the car started misbehaving) and was advised it was my EGR valve. I started my car back up to limp home, and it was fine. No shuddering, no stupidity.

I let it sit for a few days, in wait for my appointment with the mechanic, and the next time I drove it, it started trying to overheat, and all of my coolant mysteriously disappeared. No leaky puddle under where the car sat for a couple days, nothing.

Concurrently, I've been having an issue with stuttering. It stutters up hills, especially when going 40-60mph. If I lay off the gas, and then hit it again, it tends to stop stuttering.

My cooling system was flushed (which fixed my non-functional heat, just in time for spring!) and my EGR valve was replaced. They could not replicate my stuttering problem, and the coolant seemed to stay in place. I couldn't, either, for about two weeks. It's back, and worse than ever. Now, it's occasionally stuttering on flat land, and always on hills, regardless of speed.


Three questions:
I don't think it's the tranny, 'cause it shudders when it's not shifting. Am I right?
I wonder if this may be related to that nasty manifold dealie that claimed my '96 SSE.
How is this all related to my EGR valve going?

Bonus question: My fuel pump is REALLY loud. Could this stuttering be a fuel delivery issue??

Thanks in advance, awesome folks. If there's anything I forgot to mention, please let me know!

You may have multiple problems. You can try to clean your EGR valve.

If your Upper Intake Manifold has indeed failed, it's probably costing you a motor right now if you haven't parked the car and drained the oil. Time to look into that ASAP. What does the oil look like after a short drive?

This would also answer the stuttering issues.

Get your fuel pressure checked. Lower priority than the UIM problem.

I haven't parked it yet because it hasn't really seemed too similar in action to what my '96 did when the UIM went.

The EGR valve was replaced a week or two ago - Would cleaning / inspecting it now show me something valuable?

Thanks for the advice so far!!

When the UIM fails, it fills the EGR passage where it comes into the lower intake manifold. All your coolant magically disappearing at your mileage is a scream for help in my opinion.

One way to check would be to remove the EGR and slide anything small enough down the EGR to lower intake pipe. Any wetness or coolant on it would be a sure sign of upper intake failure.

Now..it is possible that your EGR is merely carboned up. A bit of throttle body or carb cleaner and a 13mm socket will fix that right up.

You need to stop driving the car and drain the oil immediately. Then check the oil for coolant. Your UIM or LIM gaskets have failed and that's the cause for the loss in coolant. Get this issue resolved FIRST, then address the other concerns, if they still exist.

Thanks for your advice, guys - Can't say I like the news, but at least I know what's wrong.