There are a few different things going on with my Camaro as of late:

• Since I got my Z28 back out of storage this spring, I've been having a lot of trouble at idle and while driving at low RPM (i.e., around town). A lot of times when I apply the gas pedal, the engine will hesitate for a few seconds and stutter, without RPMs increasing at all. Then all of a sudden it will come roaring back. Then sometimes when I am idling at a stop light, the RPMs will dip below 500 and kind of waver, then the engine will roar back up again and idle a little more evenly. When I got my car scanned last week, it was reading two codes: P0100 Mass or Volume Air Flow Circuit Malfunction and P0400 Exhaust Gas Recirculation Flow Malfunction. I also have no rear O2 sensors (no cats). Car has no such issues when I'm going highway speed.
• Since I swapped rims/tires, sometimes my car will pull hard to the right, especially when braking. It doesn't do it all the time, and it seems to do it more often when I'm on rougher roads. Might this be related to the size increase from 245 to 275 in the front?
• When I'm driving down the highway (70-80 mph), I get a strange pulsing vibration that moves through the car. It's a slow pulse, with a period of about three seconds. It almost feels as if it goes from the front of the car to the rear.

If anybody could give me any input on any or all of these issues, I would greatly appreciate it!

 

check your air intake to make sure you dont have any visitors shacking up in there. look the maf over to see if its lookin sad and dirty. if you know anyone with a abs scanner try scanning for abs codes.

 

The EGR is only supposed to operate during mid-range rpm's (not at idle or WOT), so no you wouldn't notice on the highway if it was bad. Since you have a malfunction code for the EGR, get that taken care of before you start chasing your tail.

 

This part here:

...is similar to how my '94 was acting when I needed to replace the opti.

 

I did have a mouse nest under the hood, but I doubt anything could've gotten into the intake itself. And what would an ABS scanner do in this situation? ABS/TC hasn't worked in years, and last time I tried to have it scanned the shop said they could not communicate at all with the ABS module.

It's been throwing the EGR code for a long time, well before these other issues came to light.

Can anybody else confirm? First I've heard anybody say the opti may be to blame for this.

 

The pulling to the right could be caused by a sticking caliper or bad brake hose on that side if it only does it while braking.

 

you may want to take the abs unit out. could be opti, could not as well. pull the air filter and make sure it doesnt have anything in there. make sure the critters didnt get any wiring. better look under dash for any signs of the hairy little intruders. check coolant level, look for any signs of water or coolant on the opti. if you cant find anything it would be a good idea to pull the opti cap and look for any signs of moisture.

 

the idle problems could def be the egr valve. Maybe the solenoid too, im not sure if it would pull a different code if the solenoid failed to function. But the egr could be clogged holding the spring open or the lines could be restricted from carbon build up. This may also be contributing to the highway pulsation if the valve is stuck in one position and is not opening all the way when it should be or closing when it should be closed. It can effect more than just the idle in that situation. That and the maf issue together are most likely the cause of your drive ability issues. The pulling could also definately be what MK said.

 

^^^ i think you got this one gm

 

Hmmmmm.....the EGR is suspect eh? There seems to be an echo in this room...room...room!