MacOS – El Capitan causing built-in trackpad and keyboard to freeze intermittently

I have a MacBook Pro 15" Early 2008, 2x 2GB RAM. Since upgrading to El Capitan including update 10.11.1 the built-in keyboard and multitouch trackpad freeze intermittently for about 4 seconds randomly at least once every 60 seconds. Booting from an external drive with Yosemite or Mountain Lion doesn't exhibit this issue so the hardware is fine. Using a bluetooth Magic Trackpad in El Capitan also works fine. I've reset PRAM and SMC. If I don't type or touch the built-in trackpad, interacting using only the Magic Trackpad then there are no stalls and no Console error messages but when using the built-ins at random intervals at least once every 60 seconds the keyboard pauses and loses all keystrokes entered during the interval, and the pointer freezes then eventually snaps to a new location. So, the system is unusable with El Capitan.

• Have reinstalled El Capitan 10.11.1 twice after reformatting the internal HD. Disk Utility reports no problems with the drive.

  No third party software, hardware or kernel extensions are installed,
  either at the system or user level – LaunchAgents & LaunchDaemons are
  empty.

  The only Login Item is iTunesHelper (unchecked). This appears to be the default.

  It's a pure, plain and simple default Apple install onto the
  reformatted OEM internal HD.

  Interestingly this issue even occurs when booting the 10.11 Recovery
  environment, and during the El Capitan installer.

Running in normal user mode with the Console open displays the following messages every time a freeze occurs, which you can deduce is filling up this log:

11/1/15 7:57:04.000 PM kernel[0]: AppleUSBMultitouchDriver::_deviceGetReport - DeviceRequest returned error 0xe00002cd (interface 0, reportID 0x0)
11/1/15 7:57:04.000 PM kernel[0]: AppleUSBMultitouchDriver::handleSuspend - SuspendPort returned error 0xe00002e2.
11/1/15 7:57:06.000 PM kernel[0]: AppleUSBMultitouchDriver::handleReport - not in path binary mode, received 0x44 data packet of length 54
11/1/15 7:57:20.000 PM kernel[0]: USBF:    7969.165    IOUSBHIDDriver(AppleUSBMultitouchDriverNoShim)::RearmInterruptRead  returning error 0xe00002d8 (device is not ready), not issuing any reads to device

Any suggestions on what else to try or investigate to debug this? It's as if the Apple native IOUSBHID or multitouch driver shipping with El Capitan is incompatible with this (aka my) older MBP. If it didn't still work fine when booting with the earlier OS versions I'd think it was faulty hardware.