Z28 having some issues...

[alone_and_insane]

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!

[meissen]

275 tires will "follow the lines of the road" so you'll notice yourself "fighting" the steering wheel more with 275 compared to 245s. My dad went from 245 to 275 and back to 245, he was just telling me yesterday how much nicer it is driving with 245s again because he's not fighting the pull of the tires.

[1999Black_Z28]

I've noticed the same thing with 275's up front and recently switched back to 245's and the problem went away...

[98blackbeauty]

Sounds like idle and surge back could be vacuumn leak. Do you still have emissions on car?
the tire pull sounds like several things, did you have tires balanced when you swapped them? and check suspention parts, ie ball joints tie rod end. New stiffer tire could exagerate worn parts.

[alone_and_insane]

Sounds like idle and surge back could be vacuumn leak. Do you still have emissions on car?

Only emissions stuff I've removed is the catalysts. EGR and AIR are still there, though the EGR has been throwing that code for quite some time without any apparent detriment to how the car was running.

the tire pull sounds like several things, did you have tires balanced when you swapped them? and check suspention parts, ie ball joints tie rod end. New stiffer tire could exagerate worn parts.

Tires were balanced when they were mounted at Discount Tire. I've had at least two shops tell me that my rack and pinion are bad (and therefore wouldn't do an alignment), but the guy who finally did the alignment said they were fine.