Currently been suffering from my 86 idle surging as soon as it warms up. Coasting it immediately will start hunting from 1k - 1600 rpms repeatedly cutting out. I already have the Iacv deleted and blocked off so I'm not too sure what it is.

Next problem is driving longer than 20 mins causes my temp gauge to shoot up high, but if I keep driving it quickly drops down. (almost looks like a tach redlining) . It doesn't seem like there is a leak from the radiator and cooling system, but the overflow will fill up. Recently swapped out my water pump and thermostat so can't see what the problem is..

Any info is much appreciated! I have about a week to get this solved before I go back to school and I need my rolla to be reliable, otherwise I may have to just sell it

Make sure you bleed the system as best as you possibly can, seems like that may be the issue. I've had these issues as well, but turns out my radiator was leaking slightly. After replacing the radiator and both coolant hoses and bleeding the system for 20 minutes, the car runs like a dream!

I'll try that out thanks. Any ideas on idle hunting?

Have you tried changing your radiator cap

http://www.mr2.com/forums/mk-1-mr2-aw11 ... hread.html

Surging is a symptom of high idle. High idle is caused by too much air getting past the TB. Vacuum leak, throttle plate stuck open a little, idle improperly adjusted, etc.

Why did you bypass the ISC? Are you sure it's completely blocked off?

Did you use an OEM tstat? Did the behavior change at all when you did?

I'm going to have to second Yosh on this one. go through your throttle body and make sure it's clean, the ports arent blocked, and the plate is closing correctly, and you don't have any broken vacuum lines. I'm also wondering why you've bypassed your IAC...