I have a 2004 Alero with a 3.4L engine and 4T45-E automatic transmission that is experiencing a couple of issues. I'm not sure if the problems are related. It does not seem like they are to me, but I thought I would post them both here just in case.
I'd first like to mention that the car is not throwing any trouble codes.
The first issue is related to how the car idles once it is warmed up. After I have been driving for a while and I get caught at a stop light the car will idle fine for a little bit then it will stall out and the rpms will drop significantly. Most of the time it recovers and does not completely die, but it has died a few times. Again, this does not happen until the car is completely warmed up and it happens intermittently. In order to try to solve this issue I have removed and cleaned the throttle body, replaced the IAC valve, cleaned the MAF sensor, and checked for vacuum leaks (just did this visually and by ear and did not find anything that seemed abnormal). None of this did anything to resolve the problem. So, at this point I'm not sure how to proceed and any suggestions would be appreciated. The last thing I wanted to mention that may be related to this problem is that my battery is on its last legs and needs to be replaced, but I haven't been able to do so because of tight finances. I know it is on its last legs because its voltage is low (around 12.3V, it is an Optima Yellow Top and should be around 13V) and the car is sluggish to start (normally takes a few seconds of cranking).
The second issue occurs on the highway and is most noticeable when cruise control is activated. Basically, the problem occurs when I have just eclipsed the top of a hill and start to go down the other side. There is some sort of hesitation/resistance where it almost feels like I tapped the brakes firmly. There is no noticeable change in rpms on the tachometer and no noticeable change in speed on the speedometer either. This has been occurring for a few months and seems to be getting more pronounced as time goes on. However, the condition is intermittent at best. I'm not sure, but it seems like this might be related to the transmission (this has happened in both 3rd and 4th gears). The car has 80K miles on it and I had the tranny flushed and filter changed at 50K. I also checked the tranny fluid and the level was fine and the fluid seemed to be in good condition. Without any trouble codes I am really at a loss as how to proceed so, again, any ideas would be appreciated.
I apologize for the long-winded post, but I wanted to be as detailed as possible. Thanks for your time.