Lately I have been getting a small rpm spike while cruising in D in between 40 and 45mph.Spike is about 200 from 1500rpms to 1700-1800.Does anyone think it might be the IAC?I have a 98 Z,auto,125k,and the HO mani and T.B. swap with no vac. leaks. as far as I know.Also the car has been hesitating at the line if
I try to take off slow.Thanks for any help.



15.2@89mph 2.171 60ft. 9.830 1/8 R.I.P. "LULU"

bump



15.2@89mph 2.171 60ft. 9.830 1/8 R.I.P. "LULU"

no one?



15.2@89mph 2.171 60ft. 9.830 1/8 R.I.P. "LULU"

Is there any way this is a downshift to 3rd?

If not, I'd suspect your torque converter lockup solenoid. The transmission might be slipping in and out of lockup.

2002 Cavalier 2200 5spd

Well,I figured the IAC but now that you mention the trans.(auto) if I drop it into 3rd it downshifts pretty hard,I don't think it has to do with the Shiftplus either but could be.Also when I am in drive and driving slow and not on the accelerator the car bogs really bad in first,I mean it sounds and feels like the trans. is on it's way out.



15.2@89mph 2.171 60ft. 9.830 1/8 R.I.P. "LULU"

What is the IAC? and did your car pop any codes or have the check engine light come on?