[1986TBIRDV8]

Hey all, first time on this board...

Anyway, My '86 Thunderbird has been acting up recently. It has a 302 (5.0L) V8 in it and she starts with near perfection but then it goes to crap from there. When she idles normally, it's around 400 rpms steady. Then it'll jump up to and sometimes over 1,000 and then back down to even 200 rpms. Sometimes it'll kill too. The real problem is when I put it into gear. It's rpms will drop so low, I can't tell if it's running or not. Then, a lot of the times it will just take a crap on me and kill once again. The dashboard is all digital and when it kills, the oil bar (says how much oil I got in the car) will say that I have no oil when in reality it's fine. The other day, I put straight through exhaust on straight out of the manifolds. Maybe I got rid of to much backpressure and brought the idle down too low??? Thanks in advance.