Well, I just had another shop take a look at the X.
They found 1 crack plug (has been replaced), and they determined that the FPR was bad. Already replaced the FPR back in Sept. '02, but had them replace it just in case.
The X now has a considerable amount of it's power back, but not all the power it should. I no longer receive a buck or stumble, but it still seems to slightly bog down. The problem (lack of power), is still most consistant below 1700 RPM's,which the speedo is around 30-40mph (o/d off) or 40-50 (o/d on), and hills still seem to be a struggle to climb. These symptoms seem to come more often when I try to accelerate from a cruising or coasting speed in the above speed ranges. I know when the problem is going to occur, because the exhaust tone gets a lot deeper and echos throught the cab (deeper than normal tone) which is either right after the Torque Converter locks up or when it shifts into 3rd gear (feels like the truck shifts or locks the TC). When this happens, the engine tone seems to change and I get a vibration through the gas pedal. Also when this occurs, the gas pedal becomes squishy/spongy/soft or less restrictive than usual.
I'm glad to have a lot of the power back, but the X is still not running as it should.
A Dodge Caravan made me look like I was standing still last night when we were climbing a hill. We both took off from the same stop light, and I was giving the X about 3/4 throttle, but the Caravan just left me behind. This is crazy, V8 X vs. V6 Caravan and the Caravan takes the X.
Any thoughts on where to go next would be beneficial.
Replaced: EGR, TPS, IAC, FPR (twice), 4 O2's, 8 Plugs & Wires, Fuel Filter, PCV, reflashed the PCM (by Ford) and cleaned the MAF. Each item has seemed to give a little power back, but not to fix the problem.
Again this is a 1999 X V8 AWD w/AT @61K-miles.
Oh, and I'm still averaging 13mpg (city) where prior to the problem I would average 16mpg (city).
Thanks again for all the support and help! Just wish I could get this V8 X to act like a V8 X.