When a vehicle needs repairs of one sort or another, it rarely just dies while on the highway, or refuses to start altogether. Instead, you may notice certain signs of that needed repair, including poor handling, odd smells, and other such issues. While only your mechanic can accurately diagnose any issue with your car, you might note some troubleshooting tips that can help you know what to expect when it comes to those needed repairs and when they might be urgent.
If your car needs a bit of extra gas to start, and then idles rough or even stalls when you're sitting in traffic, this can be caused by a faulty EGR valve. This valve controls what is called exhaust gas recirculation, which recirculates a portion of the exhaust from the engine back to the engine compartment itself to dilute the oxygen coming into the engine. If that valve is faulty, oxygen may build up in the engine, or the valve may be recirculating too much exhaust to the engine so that the fuel-to-oxygen ratio is faulty. In turn, the engine's idle will be rough, or it will stall. Having this valve replaced can address this problem.
Loss of power
If your vehicle loses power when you accelerate, this can mean poor fuel quality; filling up with a better-quality fuel and using an additive that cleans the engine, can help to correct this problem. However, the car might also have damage to the linkage of the transmission cable. This cable is what changes the gears of the car, and when its linkage is worn or damage, the car may actually slip between neutral and drive, causing a loss of power. If the car tends to jerk or slam into gear, this is also an indication that the transmission cable needs replacing.
If you hear a scraping sound from the front of the car while driving, this often indicates a problem with the vehicle's brakes. The rotors or brake pads may be worn down, but if these pieces are relatively new and shouldn't yet be worn, they could be contaminated with grease, dust and other such substances. This can cause a metal scraping sound whether or not you're actually applying the brakes, as the pads can be consistently caught against the rotors when they're contaminated with debris. Ignoring this problem can mean a sudden failure of the braking system, so have this checked as soon as you notice this sound.
Contact a vehicle repair service for additional advice.