pgt96w99k

Hi i have had my 96 probe gt 5spd since 50k (currently 98500miles) and have had some of the regurlar issues associated with probes ie: water pump, ingnition set, clutch. All of which i had replaced, and havent had problems until i started hearing belt noise... so i took it to my mechanic (who i have been dealing with for 2yrs now satisfactorily) and he told me pretty much what i new... timing bet tensioners ac/belt, couple misc associated with those and i had him do the water pump again since it went out on me at 55k...all and all i was happy no more noise and better performance, except when idling after start or warmed the car jerks alittle and the rpms dip almost to 0... usually hovers around 1st/2nd line...i started testing wether it was draw from my amplifers... and i tried putting on headlights ac etc and that actually fixed the idling cuz it bumped it up a few notches.... but with nothing electrical on or just radio...it would dip at idle and at one point the CE light came on... i took it back to my mechaninc to check the idle/work he just did the very next day after getting it back from 1st job. He told me it was 99.9% my alternator after running it thru diagnostix and coming up clean... voltage on the alt was a few pts low.. i was hesitant about this because i wasnt' sure it was the problem...

Alternator is in ...

i have a 2nd battery in the trunk and a isolater between the alternator and the 2 battereis to power both... my mechanic now wants to replace the isolater...(which i put in my self when i purchased the car 4 yrs ago...) and i believe he kept the new alternator in the car....


Am i obliged to pay for the alternator if the problem is really the isolater or something else??

Are alternators problematic with probes and should i just keep the new one to forgoe a headache later?

Any suggestions as to my problem with the idle??

thanks alot and sorry for the long story :)