I started the car then the gas engine came on roughly and the whole car shaked for a few seconds then back to idle but still relateively noisy than normal. What could be wrong? Thanks.

 

Not enough to go on. Lots of stuff could cause that. An ISC reset might help, but Dirty oil, Air filter, Spark plugs, the list goes on....Also a worn torsion strut on top of engine....The movement of the engine can make it feel rough.

 

Any check engine lights? That's what mine did after spark plug changes. Ended up being a bad coil pack (under intake manifold).....

 

It seems fine again at this time, no check engine light, the car is almost 110k miles and is due to change the spark plugs/ timing belts etc. Any good diy instructions?

 

There is a DIYs on this forum for both plugs and timing belt. Basically you remove the cowl under the wipers and all the intake manifold stuff. You then can sort of get to the rear plugs. I would do the timing belt at the same time as having the cowl off makes it slightly easier to see the rear cam sprocket. With the plugs removed, it is easier to spin the engine if needed.

Before you order parts look at the side of the engine from the passenger wheel well. If you see any pink crust you may also need a water pump. I changed only my belt but then had an idler go bad a few months later. I am still on my original pump, tensioner and seals at 135k miles. You will need an air impact wrench to get the main crank bolt out.

 

For the cost of the pump and pulleys, I'd replace those at the same time as the timing belt. When I asked my dealer about the seals, they said they normally leave those alone unless they are leaking. "Better to leave them alone" if no signs.

 

Also, did you get my PM message on more details to do the plugs? Because I just registered, some of my PM's and posts have been delayed so they can first be approved....