Hard acceleration stumble...

[82Stang]

Hi,

96 Ford Taurus 3.0L OHV auto. Car runs fine normally, but when accelerating hard, uphill or any good load, it will act as if it won't increase in speed and just gradually decrease in speed. Up hills and hot weather seem to antagonize this. Hot or cold I can make it stumble whenever I accelerate hard. Not sure, but might hear some sizzling or sparking noise, but very very light and hardly noticeable so might be just me hearing something that isn't there. There seems to be a temp guage fluctuation sometimes during this.

Coolant is full. New ignition coil, spark plugs, wires, thermostat, EGR valve, EGR modulator, (3) O2 sensors(front engine, back engine and next to converter), Fuel filter(1 yr old). I scan it repeatedly after monkeying to see if anything shoes up, but nothing, no codes.

I'm on my last marble trying to figure this out. Any ideas?
Thanks.

[TaurusKing]

How about fuel pressure??? Those parts you replaced, was replacemant indicated or just for the H of it??? Don't needlessly replace unless diagnosis shows the need..

[82Stang]

Yep, they needed replacing. Various codes led me to change them. But no codes now and still have same old problem. I am thinking either fuel related(filter again, dirty injectors) or possibly converter going bad.??

[shorod]

I'd suggest pulling the intake air hose from the throttle body, manually open the throttle plate and check for carbon. If there's a fair amount of build up on the back of the throttle plate or inside the upper intake. Also, consider cleaning the Mass Air Flow (MAF) carefully and of course make sure the air filter is not restricted.

If your scan tool has a datastream mode or if you have a voltmeter, make sure your Throttle Position Sensor (TPS) responds linearly to throttle input.

-Rod

[mwt47]

I would check fuel pressure.

Mike