Originally Posted by slipstream444

It's a machine, and moods have nothing to do with it.

Everything you mentioned is related to the condition of your car relative to the temperatures it's experiencing and your driving habits.

The spongy brakes indicate you have air in the system. It was recently serviced... but they may have not removed all of the air. Air is compressible, brake fluid is not. When the car/brake fluid is cold, the brakes may very well feel relatively normal. However, when the brake fluid heats up (even slightly) the air expands and the brakes get much more spongy. Brake fluid needs to be changed out every 1-2 years (depending on your driving conditions and the average relative humidity in your area) due to the fact it absorbs water. That absorbed water also contributes to the spongy feel when it gets hot enough.

1st gear has the smallest forward gear synchro, and that synchro is really not designed to be used for much more than the initial engagement, and the rare downshift to assist in very tight and slow turns. I never use first for motor braking, and rarely find a turn I can't take in 2nd - especially at speed. Rough engagement in first at a stop is usually an indication you're trying to jam it into gear too quickly. In that case, the first gear synchro is trying to take the transmission input shaft (to include the disc) from idle RPM and stop it instantly. The synchro is essentially a very small shaft brake (the conical portion is similar in principle to a very small dynamic/wet clutch) and it's job is to slow down or speed up the input shaft and clutch disc (depending on whether you're upshifting or downshifting) to match the throughput speed of the output shaft based on the gear being selected. Therefore, if you're jamming the shifter into first at a stop, the first gear synchro has to bring the input shaft to a sudden stop. This results in a loud thud and some driveline shudder. If you're revving the engine in neutral with the clutch out - and then quickly push in the clutch and try to jam it into first gear quickly - this only aggravates the problem because now the first gear synchro has to absorb even more energy.
Smoother and slower engagement usually solves most first gear engagement problems - IOW: press in the clutch pedal, WAIT a second or two (this allows the input shaft to start to slow down), and then smoothly put the car into first.

Why is it easier to select another gear prior to placing the shifter in first? That's an easy answer: All the other forward gear synchros are more robust and can more easily stop the input shaft and disc much more easily than the first gear synchro at a stop. The principle is the same for reverse - which has an even smaller synchro. This is a technique that I was shown by my father to reduce wear on the first gear synchro and to manage a tricky reverse gear.

Again, as with your brake fluid, your clutch fluid may not have been serviced properly and might be contributing to the problem.

Power and fuel mileage problems can be an indication of several possible problems and be caused by too many variables to mention. Fuel quality, condition of your spark plugs (you mentioned they were replaced - were they replaced with OEM plugs?), extreme cold (thickening of the oil and other driveline fluids), and other temperature related problems, etc. can all play a part. The biggest variable for fuel mileage is YOU. Small changes in conditions and the way you react to those conditions can have a huge influence on fuel mileage.
Again, power loss can be so many things that it would be hard to post them all. Heat soak, MAP issues, condition of your spark plugs, cheap gas, plugged injectors... Those could be some of the issues.

Most of these problems you typically start to see at the transition of the seasons (hot to cold - cold to hot), so temperature is probably a player. If you've had a couple of warmer days recently and then started to notice the problems or the problems became more pronounced, then this should make more sense.