When i start the car cold, it revs up to 1400rpms and drops down to about 700 normally. Then once driving it sometimes drops to right about 500rpms and sometimes all the time up to 900 when just at normal traffic light stopped in drive. The varation happens almost everytime im out driving, even after a full warm up of the car. The drive is still normal, however i do notice sometimes a lack of power, not alot but alittle. Another issue is the drop and rise in rpms when i turn on and off certain things in the car. ie, seat warmers, heat from the vents, and a big change in rpms from the headlights on and esspecially off. Could this be the alternator?

 

you can check the voltage from the altenator if it throwing more 12.8 or more its okay. Do a full tune up, spark plugs and wires, cap and rotor, fuel filter and air filter, clean the throttle body.

 

I just did all of that besides cap and rotor less than 1000 miles ago. Will any voltameter work for the alternator or is there a certain kind? I haven't checked one before so a DIY would be great. thanks for helping out the n00b in me

 

Sounds like idle air control valve. The voltage thing is the alternator running too slowly and "dropping out". Ignore that, it's a symptom, not the cause.
Also look for vacuum leaks.

Regards, Andrew.

 

Yeah i was gonna suggest to check the Idle Valve. You can take it out and clean it try usind WD-40 for lubrication purposes ..CHeck all the hoses for vacuum lines. You can spray carb cleaner through the engine if the engine accelerates when you spray the carb cleaner you have a leak somewhere. try doing through the vacuum lines.. Hope this helps I did it on my 89 240 and found a leak..

 

I did all the vacuum hoses again last weekend just to make sure. Where is the idle control valve? Also could the brake boost check valve (the white elbow) not sure if thats the correct term, could that be the problem if its bad?

 

the idle air valve is beneath the throttle. im not sure about the brake boost valve..

 

alright thanks for the help