This is kind of a long story, so I'll try to keep it brief yet detailed.

I bought this 2003 TL Type S a few months ago off a guy and in recent weeks have began experiencing a case where the engine seems to wanna drive itself. At first, running the A/C for long durations would cause this issue, which led me to discover that the A/C drain plate is right above where the ECU is and can spill over if the drain hose is clogged; I stopped using the A/C to remediate the issue for the time being.
Just this morning I did my spark plugs and one coil pack because the old one was faulty (I couldn't afford all 6 at this time) and decided to run the car down to a coffee shop for a post-maintenance test drive. The drive went smoothly enough up until I noticed a little bit of that "pull" feeling from the car. Came home, put it in park and watched the RPM's climb steadily on their own up to about 3.5k on the meter before I called it quits and killed the ignition.
I've read up on multiple possible culprits in older threads on Acurazine for this issue: vacuum leaks in the IACV, compromised ECU due to water from the A/C, using the wrong spark plugs(?), dirty/stuck TB.
Another problem worth noting, though I'm unsure if it's related to my primary issue: Sometimes when starting the car my VSA light, CEL, and the little yellow triangle light will come on, no blinking and there is no code being thrown for VSA. My VSA light issue has never seemed to overlap with my "self driving" issue.
I have engine codes for misfires on cylinders 3, 4, 5 and one p1399 I believe, I'll have to read the codes again to be sure.

On that note, are there any 2g TL tech gurus out there that have any insights into this? I'd like to have a broader understanding of each possible thing that may be causing my "self driving" issue before I go around throwing money at parts on the other side of the car from the real problem.

 

I did replace my spark plugs with platinum alloy plugs instead of iridium because I got mixed up on which one I was supposed to use. Would this attribute to my self-driving problem?
I do plan, when I can afford it, to replace all the rest of my coil packs and get iridium spark plugs because that's simply what should be in the car, though I doubt it'll be the be all end all of this particular issue.
I appreciate any one and all's time reading this posts and offering knowledge

 

^
The below spark plugs are what Acura recommends as OEM. They can be had at a significant savings via rockauto for $4.88 each before shipping.
I have never had problems with them and never felt compelled to 'experiment' with anything other than these.

The good thing about 2G TL throttle bodies is that they are not DBW; therefore, they can be removed & cleaned thoroughly without concerns for servo issues when manipulating the butterfly valve.
Be sure to perform the idle relearn procedure.

Surging may be due to a dirty or failing IACV or a vacuum leak as mentioned. It's important to check the smaller vacuum hoses to all the motor mounts and the #11 Mount Control Solenoid connections below for deterioration / failure.


When my '03 automatic CL-S through a cylinder misfire code, the VSA light always came on and it would turn off when clearing the code.
In regards to coil over plug replacement, once gain, rockauto has the best prices out there. There is also a reasonable priced NGK & hitachi (OEM) available; however, the part numbers escape me? A quick search should find them.
Also, make sure if you have removed the upper inlet manifold cover that you replace the metal upper inlet manifold gasket with the little 'tab' toward the firewall side of the engine for proper fitment.

Good Luck