Help with troubleshooting a sluggish -96 explorer.. 200.000 km on the meter.

[SuperSwede]

I´ve had the car for a year soon. Lately it has become sluggish and “slow”. Fuel consumption has gone up through the roof, and the car seems to lack power. From a standstil on gravel it hard to get it to spin.. it just barely do and then just eases of..

My first thought was that the transmission was the problem.. I changed the oilfilter and flushed oil out via the radiator. The old oil was a sad sight.. tar black and smelly. Not a minute to late.

Not much changed.. the gears go in and out quite fine, the OD works and the rev are below 2000rpms at 90km/h. One thing I´ve notised is that it downshifts for every little reason.. a slight climb, barely noticeable can be enough. Pretty much so that if I have some wind in my back it goes just fine.. turn around and go against the wind and it downshifts !! Turns me ..
A kickdown at 90km/h for a overtake just produces a lot of noice an less action.. sure it accelerate, but not as I would expect, or it did a while ago..
Sluggish is the key word..

Some guy told me to do a test: with a warm engine , foot on the brake hard and then punch the accelerator and see if it goes over 2800rpm´s.
No it doesn´t, It cuts out at that rpm.
According to that guy that indicates that the transmission is just fine.

Perhaps I should look for the reason elsewere?

Please help me troubleshoot this one.. it gives me a great headache..
Airfilter and plugs are new..

Thanks.

 

[Opera House]

First, install a transmission cooler. The fact that it is dark means that it is overheating. This hardens the O rings and reduces clutch pressures. I buy Explorers with about 100K with nasty fluid and install a cooler. I drive them another 100K and the fluid looks as when I sell it.

Engine problems will cause excessive downshifting. That is what the control system does, shift down when it senses the engine is excessively loaded. Got a check engine light or have a slight coolant leak? I'v had problems with plugs getting a coating that shorts them out with acceleration. Acceleration requires 3X the voltage that idle does. This causes any weakness in the ignition system to show up. Do not look any further at your transmission. Provide some more engine symptoms.

 

[jremington59]

It would help to know the engine.

You said you changed plugs, but what about cap, wires and the condensor?

 

[SuperSwede]

sorry.. its a 4.0 v6

The plugs and filter was changed just a while ago as a routine.. did´nt make anything better, nor worse..
As up till now i´ve been thinking the problem was to find in the transmission..
I´m trying to get some advice on where to look for the reason now.

I don´t want to swap a load of things on a guess.. but to get some good advice from the amazingly deep source of experience here..

Tips I´ve got so fare are blocked cat´s and a faulty oxygen sensor..

Will look into it..

 

[SuperSwede]

so far: No problem with the cat´s
I cleaned and checked the MAF ,changed plugs again just to be sure, testet all the wires.. as specs.
Tested the coilpack and got 13.0 ohms on 1-5, 12.9 at 6-2 and 12.8 at the final 4-6. Is that a normal reading?

Working my way slowly..