yes i purchased a used E.H.A on ebay for $70.00 i adjusted air fuel ratio,wich took away surging idle,unfortunatley i dont have any tech tools right now,i had to sell off most of my high end tools booohoo. when i first got the car my mechanic told me to replace both fuel pumps,the fuel filter,the o2 wich i did,he said it would solve the issue,i wonder where he learned his mechanical info,i could have told him that,it didnt help.i think your right it may be the fuel mix,im going to send it back in the shop because i cannot possibly figure this issue out,they had better come up with a better diag this time.i will tell him to recheck air fuel mix,it idles at about 650 rpm,it seems kinda low to me.i feel a slack when i floor it on freeway its just not all there.

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enjoy life,take the coal that is handed to you and turn it into diamonds. { PHILLIPIANS 4:13}