singaporesam

I use my 3/4 ton pickup to tow with but even w/o a trailer it's just real sluggish. They said is was 02 sensor just we replaced that. Then it was new injectors. We replaced that. Then new fuel filter. Still runs sluggish and stumbles at slow speeds. Even stalls at times when idling or when you let off gas like driving in a parking lot.
When you step on it from a stop, it doesn't seem to really get going. Hard to explain as although it moves, it just doesn't seem likes its getting a full amount of ????? gas or electrical. Just sort of happened as it was running great.
We use high octane gas and have even added additives. Still no power.
Any thoughts or comments?
Thanks
S
1994 V8 5/7 auto, towing package, 4x4