I have and 87 Firebird, 2.8 V6 Auto. When I got it about 5 months ago it ran perfectly. For last few months, when I start the car, check engine light flashes and the RPMs, bounce. Most of the time I have to keep the gas peddle down until the car settles down. When I am driving the car will randomly show the check engine light and car will shut off. Not at all safe scicne my breaks also die out .

I just got a code 34 after the initial code 12 handshake . This pleases me couse I could not previously pull a code or get the code 12 handshake. On this model it was 3 quick flashes followed by another 4 after a pause.

Code 34 looks like stands for Low voltage (high vacuum) at mass air flow sensor (or MAP sensor)?
WHat do I check/ replace in this case?

I had gone through most of the filters when I got the car and all were new. The spark plugs I looked at look new as well.