i got a 98 dodge stratus with 198k miles but i dont know how to apply it or where to buy it

 

Do a Google search!!!

 

The most common application of seafoam is right into the gas tank, to clean the fuel injection system.
We can't be more specific for direct engine injection until you tell us what engine/trim you have (SE/ES, 2.0, 2.4, 2.5v6). And with that many miles, it might not be such a good idea to use such an aggressive agent anyways.

 

its a 98 v4 2.4

 

Yeah, i would stick with just a can in a nearly full tank of gas to clean out the fuel system. If it's running rough, a full tuneup may be in order. I would NOT do the vacuum injection (like you find on youtube blowing smoke like crazy) with that many miles. It is likely to work things loose that you don't want worked out. You are already on the high mileage side of what most others here have. I'm not too far behind you (20,000mi), and your Strat has 2 years head start on mine (2000es 2.5V6 179,xxx mi)

 

oh i c how do i clean out my fuel system? my car seems like it doesnt have power like it was before and the gears dont shift on 3000 rpm is there a big service for 200000 miles?

 

Take full can of seam foam, dump into nearly full tank of gas, drive to about 1/4 tank, fill like usual. 200k is a nice milestone, just do your standard things at the same intervals that you have obviously been doing for years.