Lately all I've done with my car is drive it to/from work and school. No racing or anything of that sort. I change my fluids regularly such as oil every 3000 miles. Tires rotated every 5000. And fill it with Chevron's premium. So I think I keep decent care of my car, but I've had a problem that concerns me. Every now and then my car will act as if something is plugged up in the exhaust or fuel or electrical is shorting. This will happen randomly and for a split second, then acts like nothing happened. For example. My car was parked in idle tonight and I was outside of it when my exhaust rattled like the car backed up and then a little pressure built and then it cleared itself without raising rpm's beyond what it was idling at, though they did dip for a second. Then about 20 minutes later I'm cruising in 5th at about 65-70 mph and the car did this again. I've had a problem like this in the past on older cars, but the problem would be fixed when I replaced the coil pack or retightened a spark plug wire onto the distributor or spark plug. This car doesn't have spark plug wires and it is coil aon spark ingition. What do you guys think? A little help please. Could a coil be going out? Could I have an obstruction in my exhaust?