code 41 and 91, cant figure it out

I know you said you pulled the injectors and changed the filter, but you might try some fuel system cleaner in the tank; I like sea-foam - you can get it at O'Reilly.

My Jeep has had similar problems and twice I've pull the O2 sensor, heated it w/ a torch a few times to clean it off and put it back in; runs fine most of the time after that and my check engine light goes off. I know you tested yours, but just kinda what worked on the Jeep.

I can't think of much that would only cause those problems for the first 20 sec and then quit. What is your timing set at? It kinda does sound like timing a little bit. 10* BTDC is stock, some like 12-14*, but each motor is different.

I had these codes for years. It's right and left HEGO's always lean. Check the orange O2 harness ground behind the intake manifold. It's usually attached to the same spot on the block that the ground strap is. It often comes off, leaving the O2's un grounded, and essentially not working. The ECU sees this as a super lean condition, and will try to correct it by making it run super rich and backing off timing.

Good luck!

unless you have access to a wideband, i would not infer anything from the A/F gauge (it could mislead you). i think of non-widebands like a voltmeter that reads from 11.5 to 12.5 volts - not very useful to diagnostics.

while running codes you have run a cylinder balance test (tests injectors).

good luck.

Cylinder balance test:
Warm the car's engine up to normal operating temperature. Use a jumper wire or paper clip to put the computer into test mode. Start the engine and let it go through the normal diagnostic tests, then quickly press the throttle to the floor. The engine RPM should exceed 2500 RPM's for a brief second. The engine RPM's will increase to about 1450-1600 RPM and hold steady. The engine will shut off power to each injector, one at a time. When it has sequenced through all 8 injectors, it will flash 99 for everything OK, or the number of the failing cylinder such as 22 for cylinder #2. Quickly pressing the throttle again up to 2500 RPM’s will cause the test to re-run with smaller qualifying figures. Do it a third time, and if the same cylinder shows up, the cylinder is weak and isn’t putting out power like it should. See the Chilton’s Shop manual for the complete test procedure

Here's the link to dump the computer codes with only a jumper wire or paper clip and the check engine light, or test light or voltmeter. I’ve used it for years, and it works great.

See http://www.troublecodes.net/Ford/
OR
See http://www.dalidesign.com/hbook/eectest.html for more descriptive help
OR
See http://www.mustangworks.com/articles/electronics/eec-iv_codes.html

For those who are intimidated by all the wires & connections, see http://www.actron.com/product_detail.php?pid=16153 for what a typical hand scanner looks like. Normal retail price is about $30 or so at Walmart.