Another possibility to check out...
There's a radius rod going forward from the suspension. It goes up forwards where it bolts into a frame member somewhere near the radiator. It's easy to overlook that, but if it's coming loose it can klunk whenever you give gas or brake. It's job is to hold the lower control arm from flexing fore-&-aft; only letting it move up & down.

Those radius rods are #9 & #11 in this picture. Check to see if the forward ends are loose.

 

I'll leave the conversation of "closed vs. open loop" as it relates to the computer operation for another day

What you are talking about is sometimes called "limp" mode.....some codes will cause the ECU to use a "defaults" to allow you to "limp the car home".

 

PROBLEM SOLVED!

"Thumping Noise While Giving Gas WHEN In Gear"
Probable cause: bad inner joint on CV axle (possibly - I don't know exactly what was wrong with the unit)



First, thank you fellas for taking the time to assist me in finding the source. The time invested on my behalf could have been with someone or something else, and as I know you men put thought into my problem, I wish there was more than saying thank you to show my appreciation...like sending you a hundred dollars apiece

I've put at least 60 miles on the car since I got the CV axle in late last night and not a single sound. Therefore, I'm convinced that it was the driver's side cv axle that was doing it. Though I had suspected it was the culprit last week when the sound was first noticed, I didn't think it was it for two reasons, being that it wasn't the symptom I was familiar with for a CV axle going bad (clicking/clunking noise while turning), and that I knew that it was going to be a big job to undertake if it was the CV axle (and it was - 1/2 hour just to hacksaw through the lower ball joint's castle nut, for example, or having to press the old ball joint out of the spindle assembly) and so I had wished to start small and work my way up big hoping it was something else. Your input and info from the web helped a lot, and over all, the car breaking down as it did was actually a good thing - my motor mount was going bad, I had a torn boot, and a few other small details.

What I think was going on that made this case different from my other CV axle I replaced almost three years ago (that one made the common noise when it went bad) is perhaps the noises come from the different joints. I'm inclined to think it's the outer joint going bad when you hear noises while turning, while it's the inner joint (the hub that connects directly into the transaxle) that's going bad when you encounter the symptom I had - thumping sound/feel while gassing only in a gear. Considering that this is the CV axle I dislocated two years ago and was able to relocate, and also taking in account that handling the dislocated prongs had a lot of grease coming out of the hub and onto my hands (I tried to salvage as much as I could back into the hub), probably what happened was that there simply just wasn't enough grease and so there was wear and tear over the course of two years. Makes me think had I bought a small tube of CV grease this whole incident could have been avoided. Oh well, as this has given me a lot of experience and after the hundreds of curse words I uttered, I feel good with the outcome. Makes me excited to make my car more new, and I'm looking forward to spending unneeded time with it in the near future.

Thanks again!
~Daniel

 

Different symptoms for inner vs outer CV joint is exactly correct.

Thanks for telling us what eventually worked out.