2000 SSEi shutters under light accelleration

2000 SSEi shutters lightly at crusing speed when I accellerate lightly, and hesitates to downshift under any accelleration and when it does it's sometimes rough. I don't know if they're related. I've replaced spark plugs and wires, fuel filter, two coil packs, CAT, water pump, motor mount, shocks, and front wheel bearing. Any help would be great. Thanks

Without an onsite road test anything from here is just a guess, sounds like possible trans issue.

Try doing a transmission flush and refill. I had a Ford pickup exhibiting the same symptoms and it was the old fluid in the torque converter. After I did the flush, the problem was gone. Hydraulic fluid is only good for about 7 years of service.

Just a thought.

GregB

For ford that would be a very common issue... Not exactly the same for a GM 4T65E...

At this point I would not recommend a flush... steer clear of that for now...

One concern I have is the car not wanting to shift... You may need to check the function of the TPS, as well check for codes revolving around the TPS.. The PCM is very dependent on seeing the load factor, if it does not have a true and correct load factor it can get very pissy... as well its possible that you could be having a PCS issue and the line pressure might be lower than wanted.. So there are a few things that really need to be looked at...

If you can't get it figured out I would recommend a good shop that has good word of mouth

Thanks guys, I'll have to get the 'tranny' checked. My only other assumption would be to check the fuel pump? because the fuel gage is also screwed up. sick of fixing the wrong problem