I am inquiring information to help me rectify a problem I have a Tuned port fuel injected 350 I have removed both catalytic converters and replaced them with test pipes the rest of the exhaust system is stock.Here is my problem the engine now oscillates between a low and high RPM idle I really have to stand on the brakes at a trafic light or even when I put the car in reverse also seems to be running very rich.
Can someone Please inform me of the correct procedure to rectify this problem and how to go about it.

 

Check for codes , sounds like an EGR problem .
I read somewhere , exhaust board maybe , that if you run big tube headers and an otherwise open exhaust that you'll lose just enough back pressure to create an EGR problem and you need to enlarge the port opening to allow more exhaust gas to flow to the EGR itself . I would head over to the exhaust board and do some research , hopefully it's something simple .

 

I had posted this also under Tech thinking I posted in wrong section but Thank you for your output also I have decided to take it to a performence shop Viprklr has been helping and I am just not sure working with tune port they are not that simple to me and I don't want to make matters worse.I am also having problem with check engine light disconnected battery and still trigers so I decided to take her in.Thanxs again




Originally Posted by Viprklr
No way. The NB is so close to the heads on stock manifolds that's there is no way that it's getting too cold. Case in point, my 88 has stock manifolds with no cat. Has been this way for 5 years now and I have no issues with it jumping in and out of open loop due to a cooling O2 sensor.

The usual place to start diagnosing an idle surge is to clean and re-set the IAC and passages. The procedure can either be found by a search or by going to the homepage and looking under tech articles.