Hi everyone. I have a 1999 V6 automatic Sport with 86,000 miles. I have an issue that has happened to me only four times so-far, but I expect more. It's very intermittent and I can't recreate it.

1st time - I was driving on a back road around some turns with overdrive off. I accelerated out of a turn doing the speed limit at half throttle when the engine seemed like it didn't want to accelerate. I pushed the gas pedal down and the more I pushed it, the more it bogged down. I let off the gas and a few seconds later, it was fine. No more issues the rest of the day.

2nd time - Came to a stop and made a right turn. About 2 seconds after I hit the gas, at about 3 mph, the truck bogged again. I floored it and nothing. Then all the sudden, it was fine.

3rd time - Going down the road, constant throttle and bogged and cleared up.

4th time - Wondering if the issue could be the cat I was waiting for it to happen again. I was accelerating down the road. It bogged down, I shifted to neutral and hit the gas. I could rev it up all I wanted. I put it back in gear and heard three thumps under the truck. After that it was fine.

When it bogs down it seems like it doesn't want to go any faster, no matter how much throttle I give it and then it clears up like nothing happened and will be fine for a few days. Grasping at straws I cleaned the contacts for the TPS and MAP sensor after the third time. I thought all was well because it didn't come back for a week or two. Then it did it again the fourth time.

I bought this truck used off my father-in-law. He took really good care of it, but I'm not sure how often the transmission fluid was changed, if ever. For what I paid for the truck, I'm definitely not going to install a new transmission. Does this sound familiar to anyone? The O2 sensors were recently replaced as well as the muffler. I was thinking maybe a clogged cat, but it happens very intermittently, I don't hear any rattles, and when it bogged down I could rev the engine with no problems.

If anyone has any ideas, I would greatly appreciate hearing from you. Thanks!

 

any check engine light ? try also cleaning the IAC it sits behind the tb

 

No check engine light. I will look at the IAC. Didn't think of that. Thanks!

 

I removed the TB and cleaned it and the IAC really well. We'll see if that helps. But, I just noticed something else I'm going to bring up in another post I think. I think my transmission is slipping... I don't know how badly.

Thanks