My 2002 SS seems to be in limp mode. Sluggish off the line strange whistling noise but not sure exactly where it’s coming from. Will shift at higher speeds. No check engine light and my diagnostic reader pulled a p0104 code (replaced the mass air flow sensor) but problems persist. No codes now. Checked for vaccuum leaks and that search came up empty. I’ve seen some stuff about solenoids in the transmission but hoping for some definitive info before diving deeper.

 

This is reminding me of the stuff I am dealing with on my daily driver, a 2004 Grand Am. In my case, I am starting to suspect a blockage in the exhaust.
Do you have ability to read data from the PCM? Such as MAF, Upstream O2, KR, fuel trims, to name a few. In my situation, I am noticing cold start, car runs great. After it warms up, my fuel trims begin to report very lean numbers and if you just tap the gas, the KR can be a couple degrees or spike to 16 degrees. As KR increases, the car retards timing and that reduces performance. Such as, my Grand Am cannot keep up very well at 60mph in its current state.
I also found at the start of this issue 3 of 6 plugs had a very wide gap, I suspect this is a sign of the issue. Too much heat possibly backing into the heads.

Side note, I recently spoke with a friend about my problem, he mentioned a clogged cat sometimes makes a sound like a Hoover vacuum. I found this video of a guy working on a 3400 Impala, and he had a whistle with his issue (at least I assumed it was a related whistle).

I have my own back pressure gauge on order and hope to test my Grand Am soon.

 

If your Catalytic Converter is clogged it will rob all the power from the car, I had the same symptoms on a 4th Gen MC I owned and I used to travel with it for my job around a 100k on it when it did that and the shop I always took it to knew exactly what it was. put on a new Cat and WALA.

 

I had a shop look at it…clogged catalytic converter. Way too expensive to replace it the conventional way. I’m in the emissions **** state of CO so going aftermarket is difficult since the websites won’t ship here. Thanks for your help!!

 

At least the problem is now figured out. In my case, it does not appear to be an exhaust blockage based on a few tests I have done. My journey continues.
Hope you can find a cost efficient solution.

 

If it’s not an exhaust blockage what are you leaning towards? I had a 1997 Grand Am GT (loved it!!) that had a lot of fuel system issues (HEET seemed to work every time). At one point the car wouldn’t start at all and that was a result of the fuel filter failing. Your issue sounds a lot more complex than simply adding HEET obviously. Learning from your experience with this could help me in the future…