PLEASE HELP.... Problems

[BowTie Eater 5 Liter]

I am having some major problems.
1. I cant grab codes ("Check Engine" never appears) or with a voltmeter.
2. My radio shuts off when i hit the braks, signal, turn heater on...
3. I cant rev past 3500 in Neutral, sometimes it wont even rev that high.
4. Some of my guages dont work( heat goes so high you cant even see needle)

Now, I have about $150, and i am thinking of getting "Autometer" guages, but im not sure...

Any help with any questions appreciated.

Thanks

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1988 Mustang GT, T-5
3.08's, No Smog Pump (Shorty Belt), Dumps At The End Of Stock H-Pipe, K&N Air Filter (Stock Air Box), Removed Air SilencerMy Stang
My Site (Not Done Yet)