2000 3.8L Hard Starting, stalls, erratic shifting

I have a 2000 Bonneville with 3.8L engine, 110,000mi. Normally it fires up immediately, but now it takes several seconds (up to 10-12) before it fires. Sometimes it idles fine, sometimes it will stall. Second symptom - when slowing to a stop, especially during turns, it will stall unexpectedly. It will restart immediately. Third symptom, most recently - erratic downshifting when slowing. After letting up on the accelerator, final downshift into first is harsh. It also sometimes surges along with the shift, jumping 100 - 200 RPM, just for a second. Driving under load or at highway speeds is no problem, and gas mileage hasn't suffered.I've tuned it up, replaced fuel filter, plugs and ignition wires and there's no service engine soon light. Thanks for any and all help

As for the starting problem, you may need to replace the Crank Positon Sensor. This should help cure the symptoms you describe. The one thing you may want to check is your fuel pressure. A bad fuel pump or fuel pressure regulator can also be a cause. Start with the fuel pressure and work from there. If the FPR is bad then replace it. It is the easiest part to change. If the fuel pressure does not come up then the fuel pump will need to be replaced. Finally, if both check out then change the CPS.

Thanks much for the quick and informative reply. I'll give it a try and let you know how it works out.

As for the starting problem, you may need to replace the Crank Positon Sensor. This should help cure the symptoms you describe. The one thing you may want to check is your fuel pressure. A bad fuel pump or fuel pressure regulator can also be a cause. Start with the fuel pressure and work from there. If the FPR is bad then replace it. It is the easiest part to change. If the fuel pressure does not come up then the fuel pump will need to be replaced. Finally, if both check out then change the CPS.

Took me a while but I finally got around to fixing this thing. GTP Dad, you were right on the money with the fuel pressure regulator, but it was kind of sneaky. When I checked the fuel pressure, it came right up to 50 pounds and stayed steady as a rock, so at first, the pump and regulator looked OK. After cleaning the Idle Air Control and EGR valves, I was checking vacuum hoses for leaks, and saw fuel coming from the vacuum connection on the FPR. Turns out the diaphragm was leaking, and although it controlled pressure to the rails just fine, it was dumping fuel right back into the intake, especially on idle. When the engine was turned off, residual fuel pressure was bleeding off directly into the throttle body, and the flooding was the source of my extended cranking problem. Replaced the FPR and all problems are gone.

Only one problem - I had a heck of a time trying to reinstall the FPR with all the internals. I could not compress the assembly enough to install the snap ring. The replacement kit came with all parts except for the spacer (if that's all it is) between the screen and the large O-ring. The only way I could get it back together was to leave out the spacer. It works just fine without it, and there are no leaks, internal or external from what I can tell. but I wonder if the internals will shift around without it installed, or if it serves any other purpose. At first I thought maybe a part was missing when a new one was not included in the kit, but maybe it's not supposed to go back in. Anyone have any ideas?

I posted this problem in a new thread before I thought of responding to this one. Sorry for the duplication. Thanks much!