I have a 1998 chevrolet silverado. When I power up hills or accelerate it feels I drop a cylinder when it goes into overdrive. When I lift off the gas pedal for about 10 seconds or so it starts running normal. My gas milage hasn't been affected or anything else that I know. It did it very rarely when I got the truck about a year ago but it has gotten worse in the last week or so. I ran fuel injector cleaner and changed my plugs. Any suggestions?
Maybe a clogged injector. Try an injector drip to clear it (you'll find it at the dealer). Fuel additive dosen't work all that well anyway.
Did all of the spark plugs look normal? It sounds to me like its time to flush the trans fluid and change the filter.
Sounds like you need a diagnostic scan for trouble codes. Your engine might be going into "limp home" mode when you place a load on it for some reason. Ever replaced your 02 sensor? Fuel filter? When you power uphill or floor it, it should drop OUT of overdrive, yes? Let us know what you find out.