i plan to adjust the valves on my 300sd but i dont have the money to buy the special wrenches. so, i was wondering if i can just use regular and stubby wrenches from harbor freight. also can anyone tell me what i need to adjust the intake and exaust too. is this job hard to do? i think mine really needs to be adjusted because it has a rough idle for at least 5min of running when cold. my gp are good and i have good compression. would the valves couse this? any info would be appreciated.