My 99 Mountaineer 5.0 AWD has been trouble free for the 40K miles that I have put on it's total mileage of 201K. It does exhibit two issues that I have not been able to resolve. 1. It has a 'stumble' or 'miss' under certain acceleration conditions. If I accelerate hard it performs as you would expect, but I don't normally drive it aggressively. If I accelerate more casually or while pulling a trailer, it will intermittently miss or stumble. It seems to be related to a high vacuum, lower rpm condition. 2. It has the 'warm restart' issue that I have seen in threads. I replaced the Engine Coolant Temp Sensor based on a previous response, with no improvement. If it is cold it starts right up. If warm, it will hesitate. If I crank it, stop, and then re-crank it will start normally nearly every time. I included both issues here in the event they could be related. Thanks in advance for any assistance.