She is starting to shake a bit around 40 & again around 50, so someone told me it might be the fuel injector. if i bought some of the stuff you pour in after getting gas, would this help me out? if so, what'* a good kind to buy from say, autozone or any local store?

I used Valvoline Max life fuel system cleaner. I use only Valveoline oil I think its a good product.

Use the valvoline, very good stuff, also dont know if you guys knew about this but Shell Oil gas stations have a new type of premium called V-Power (i work there) 5x more cleaning agents than regular premium yet same price, believe me use it, ive read all the tests and stuff and it really makes a difference, use the injector cleaner and once a month or every time you fill up use the v-power and you should be good to go, never need it again, oh it also cleans intake valves.

STP Makes a really good product also. Can't remember the name but it comes in a silver quart size bottle. it has always worked for me.

Pull the plugs and look for deposits on the electrode, this is unburnt fuel and maybe caused by a sticky injector or bad plug wire/coil.

We've heard some bad stuff about shell gasoline here with our cars. It seems those cleaners are corroding the fuel injectors and causing lots of problems?

i had a similar problem recently, some hesitating and surging under load at low rpmsk, generally right after a shift. i replaced my fuel filter, plugs, and wires and the problem seems to be solved. if you suspect its an injector, be sure to keep a close eye on your fuel mileage (which is something we should all do all the time anyway). this can be an early warning sign of an impending problem. BTW, if you haven't seen it on any of these forums, i guess bosch plugs foul more readily in our cars than other brands.