Hello, I’m still pretty new to the corvette scene and one thing I definitely noticed about my 97 A4 is that some days on starting up my car and getting on the road to work, the car feels very sluggish almost as if the rear is heavy or I’m hauling something and feels very slow to accelerate. Other days at random the car will feel completely normal and will jump straight to 20 mph with just letting go of the brakes and I only have to lightly touch the throttle to reach speed limits. I’m still learning a lot but my best guess is that this can be maybe an electrical (battery) issue? Something may not be getting enough power. NOTE: tires have less than 8k miles since I bought the car, the previous owner had no knowledge of when was the last time spark plugs were changed ( I tried changing them myself but they won’t budge), I replaced the plug wires and I replaced both downstream O2 sensors but not upstream ( no codes for those ). And lastly the previous owner replaced the battery with a Costco battery (< probably the issue) early last year which I plan to replace ASAP. Hopefully I posted this in the right thread but any info helps!

UPDATE: So I pretty much found the solution!!! Turns out it’s a very huge newbie mistake on my part . I started by replacing my air filter that was littered with a bunch of small debris, I then continued to remove my MAF to spray it clean but I couldn’t budge my Throttle body so I’ll attempt it again when I get the time, things were getting better(better acceleration but still getting that slow and laggy throttle response feel) but still not right, then i remember a friend telling me how much TIRE PRESSURE impacts performance/fuel economy. All my tires were improperly inflated to random numbers (FL, 27psi/FR, 36psi/RL,37psi/RR,34psi) After getting them all down to 32 cold BAM, car feeling very responsive, doesn’t feel heavy, and accelerates just fine without having to toss that throttle down. Roads feel much smoother and my steering is even feeling better assisted at high speeds.

 

There can be several things that may cause the car to be sluggish or low on power...fuel pressure, dirty MAF or throttle body, knock sensor retarding timing, a cat that may be getting clogged (restricted exhaust)...being a random loss of power this may be a difficult to diagnose without a scope…don't think it's a battery issue but it always a good idea to get it checked anyway if you don't know it's status...the downstream O2 sensors are not involved in "fuel control" of the engine...the upstreams are...do you have a scan tool ??...if so there are a few Data Pids you can look at to maybe narrow this down...if you don't you'll just be changing parts and that may get expensive !!...if the plugs are bad they will usually throw a P0300 for random misfires and they shouldn't be very hard to remove...maybe try a rachet with a little longer handle…taking the shop to a diagnostic shop may be your best bet…paying for an hours diagnostic time may be cheaper than replacing a bunch of parts !!

 

I have tested some things out and so far the only difference I’ve felt is when I switch off TC the car does feel “lighter”. And I took a look at my air filter seeing as my area is nothing but dirt and rocks (occasional dust storms) and that thing is cluttered! with tiny pebbles, dust, and leaves. Could this probably be an alignment issue and just cleaning/replacing air filter MAF and TB?

 

I’d first see if you have any codes stored..you can access them through the DIC…there are a few YouTube videos on how to do this…without at least a scan tool you’ll be guessing…I would replace the air filter and clean your MAF sensor and TB…don’t just start replacing parts !!

 

Not saying this is your issue but I had the same thing happen to me, no codes nothing. Some days it would pull hard, others it's like I'm pulling a trailer. Well I pulled my traction control fuses and problem is gone. From what I read it closes your throttle, applys the brakes and cuts timing. Even before all the mods I had this problem when my car was completely stock. Hope this helps