Ford published this article in Jan 14 2002 going back to some 1992 vehicles and beyond (1995-2000 2.5L Contour/Mystique) Ford stated to start using 5w-20 for EPA and CAFE reason ( fuel economy ). Every auto manufacturer gets measured on average fuel economy, not by vehicle but overall. If they do not meet the regulation they get a hefty fine. 
 
The 5W-20 had nothing to do with power just fuel economy requirements.
 
I doubt going to 10W-40 from 5w-30 has anything to do with your sluggishness! 
 
Since you were getting as much oil in the catch your secondaries may be hanging up, or the cats may be starting to clog.
 
Here is the notification:
ISSUE:
Ford Motor Company now recommends SAE 5W-20 viscosity grade for servicing most gasoline and flexible fueled vehicles. 
 
ACTION:
All 2001 and 2002 vehicles where SAE 5W-20 is specified should be serviced at the recommended oil change intervals using SAE 5W-20. This oil is an improved formulation to improve fuel economy. Testing has validated this viscosity grade can be used in many previous model year vehicles. It is recommended ALL vehicles on the following Vehicle Application Listing be service with SAE 5W-20. 
 
All 2001-2002 vehicles other than those listed in the "Exception 2001 Vehicles" or "Exception 2002 Vehicles" chart are being filled with SAE 5W-20 motor oil at the factory and should also be serviced with SAE 5W-20 oil. 
 
Vehicle Application Listing Approved For SAE 5W-20 Motor Oil 
1993-1996 1.9L Escort/Tracer 
1995-2000 2.0L Zetec Contour/Mystique 
1999-2002 2.0L Cougar 
1997-2002 2.0L Escort/Tracer 
1998-2002 2.0L Escort ZX2 
2000-2002 2.0L Focus 
2001-2002 2.0L Escape 
1993-1997 2.3L Ranger 
1993-1994 2.3L Mustang 
1993-1994 2.3L Tempo/Topaz 
1998-2001 2.5L Ranger 
1995-2000 2.5L Contour/Mystique 
1999-2002 2.5L Cougar 
2001-2002 3.0L 4V Escape 
1996-2001 3.0L 4V Taurus/Sable 
1993-2002 3.0L (Vulcan) Aerostar/Ranger, Taurus/Sable (Flexible Fuel and Gas) 
1995-2000 3.0L (Vulcan) Windstar 
1993-1994 3.0L (Vulcan) Tempo/Topaz 
2000-2002 3.0L 4V Lincoln LS 
1995-2002 3.8L Windstar 
1993-1997 3.8L Taurus/Sable, Thunderbird/Cougar, Continental 
1994-2002 3.8L Mustang 
2002-2002 3.9L 4V Lincoln LS 
1997-2002 4.2L (SPI) F-150 (under 8500 GVW only), E-Series 
1996-2002 4.6L 2V Mustang 
1992-2002 4.6L Crown Victoria/Grand Marquis 
1991-2002 4.6L Town Car 
1994-1997 4.6L 2V Thunderbird/Cougar 
1996-2002 4.6L 4V Mustang Cobra 
1995-2002 4.6L 4V Continental 
1993-1998 4.6L 4V Mark VIII 
1997-2002 4.6L 2V Triton F-150/250 (under 8500 GVW only), E-Series, Expedition 
1993-1999 4.9L E-Series, F-Series 
1993-1995 5.0L Mustang/Mustang Cobra 
1993-1993 5.0L Thunderbird/Cougar 
1997-2001 5.0L Explorer/Mountaineer 
1993-1996 5.0L E-Series, F-Series, Bronco 
 
 
 
 
2000-2002 5.4L Excursion 
1998-2002 5.4L 2V/4V Navigator 
1997-2002 5.4L 2V F-150/250 (under 8500 GVW only), Expedition, E-Series, E-350 Chassis/RV/Cutaway 
1993-1997 5.8L F-Series, Bronco 
1993-1996 5.8L E-Series 
2000-2002 6.8L Excursion 
1997-2002 6.8L E-Series, E-350 Chassis/RV/Cutaway 
1999-2002 6.8L Super Duty F-Series 250 HD/350/450/550 Motorhome 
1993-1998 7.5L All Vehicles 
NOTE: FOR 1993 THROUGH 1998 MODEL YEAR FFV USE XO-10W30-FFV. 
 
 
 
NOTE: THE "EXCEPTION 2001-2002 VEHICLES" SHOULD BE SERVICED WITH SAE 5W-30 MOTOR OIL. 
 
 
 
Exception 2001 Vehicles 
 
Engine Vehicle 
3.3L Villager 
3.9L Lincoln LS 
4.0L Ranger, Explorer/Mountaineer, Explorer Sport, and Explorer Sport Trac 
 
Exception 2002 Vehicles 
 
Engine Vehicle 
2.0L HP Zetec SVT Focus 
3.3L Villager 
4.0L Ranger, Explorer/Mountaineer, Explorer Sport, and Explorer Sport Trac 
 
NOTE: IF VEHICLE IS NOT LISTED IN THIS APPLICATION, SAE 5W-30 OIL IS RECOMMENDED. REFER TO TSB 99-8-16. 
 
 
 
PART NUMBER PART NAME 
XO-5W20-QSP SAE 5W-20 Motor Oil - Quart (USA) 
CXO-5W20-LSP12 SAE 5W-20 Motor Oil - Litre (Canada) 
XO-5W20-5QSP SAE 5W-20 Motor Oil - 5 Quart Jug (USA) 
XO-5W20-DSP SAE 5W-20 Motor Oil - 55 Gallon Drum (USA) 
CXO-5W20-DBSP SAE 5W-20 Motor Oil - 205 Litre Drum (Canada)