The simpliest thing to find is your LFT numbers. If the value is negative then you are running rich. From there you can start to track down why.

A bad 02 sensor would throw a cell. A bad fuel pump, or clogged fuel filter would not. (Ethanol tends to clog fuel filters and cut the life drastically) If your injectors were stuck you would be flooding the engine, and your idle would be just horrible.

If you can though with an OBDII reader you could possibly see what the reading of the O2 sensors are. With old sensors they become lean bias.

Everything is old on the car. Did you check for an intake leak or a vacuum leak? These are very common with bad idles, bad AFR, and bad fuel mileage. Did they use the old or new gaskets on the intake when they put your engine back together? If there is a leak of air being sucked into the system any number of places from oil/fuel injectors to the intake it would results in problems with performance and/or fuel mileage.

First check and clean the EGR valve(prone to carbon build up causes them to not read properly), along with the SSV. Youve done this before so you should know how. With both of those off check the fuel and oil injectors. Then reinstall everything properly. Start the car and let it warm up for about 5 mins. Then take a bottle of carb cleaner. Spray the carb cleaner everywhere along the intake. I mean every area you can get to needs to be throughly sprayed with carb cleaner. If you notice a change in idle (have someone watch the tach or listen very closely) then you have a leak. If everything turns out to be clean then move on. (A tiny carbon build up on the EGR can cause poor fuel mileage, along with even the smallest of air leaks. This causes a change in the Air/Fuel mixture.)

If this was a carbed vehicle you would see a drop in power, but since we are electronically controlled the changes in your fuel mixture might be from a minor leak that the computer is correcting. I would start there. Make sure everything seated up properly, and all the gaskets are new and crushed properly. Then I would check the fuel pump, fuel filter.

If all of those turn out to be ok then I would start asking about your clutch. Even though it may seem odd but ask the tech that reinstalled your clutch the condition it was in. Is the flywheel hot spotted? Is the clutch glazed? Its not a common problem but it does happen.

You need to clean the EGR/SSV/Idle Port valves anyways if it wasn't done on your new engine install.

 

The RX8 does not have an EGR valve or system for that matter. Checking your SSV takes two seconds. Does it feel like you hit a wall at a certain RPM and power just stops? Get a short log at cruise in gear man.

 

The RX8 does have an EGR its just internal.

"2.The use of the side exhaust port and the cut-off seal,
etc reduced internal EGR and improved combustion at
low speed and light load range, leading to the drastic
improvement in the fuel economy performance"

Read the PDF found here, page 8:http://www.rotarydevelopment.net/Rot...790_Rotary.pdf

I can't copy and paste at work it wont let us download but the RX8 does have an Internal EGR.

 

Dude, just admit when you are wrong. I have read that document. There is no EGR valve, you said to clean the EGR valve. There is no EGR system really.

 

Should have the log in a hour.

 

Logs look normal to me (didn't check all of them ) .
Nothing is leaping out at me ......