2005 Impala....Car started to vary in engine performance

The car started varying in engine performance as in running normal for a bit
then act like its running at 80% not really dieling all together but
noticable. Also the speedo will start bouncing around when this happens. Any
ideas I did run some injector cleaner (no changes)and I will change the fuel
filter next.



__________ Information from ESET NOD32 Antivirus, version of virus signature database 5193 (20100613) __________

The message was checked by ESET NOD32 Antivirus.

http://www.eset.com

Mike Sanford wrote:
> The car started varying in engine performance as in running normal for a bit
> then act like its running at 80% not really dieling all together but
> noticable. Also the speedo will start bouncing around when this happens. Any
> ideas I did run some injector cleaner (no changes)and I will change the fuel
> filter next.

Make sure the engine and ecu are grounded very well.
Check the alternator for a bad diode.