Ok, so I bought this Blazer for $700. The problem with it is when traveling down the road at a steady 35mph, the engine spins near 1,100rpm'* and it begins to misfire. The misfire goes away if I accelerate. The engine runs fine at all other speeds. If for example, I am accelerating beyond 35mph the engine wont misfire near that particular rpm, but if I try to maintain a steady speed of 35 the misfires start happening.

Things the previous owner replaced trying to fix this problem are:
EVAP purge canister.
EVAP purge solenoid.
Spark plugs.
Distributor cap.
Complete distributor.
PCV Valve.
Throttle Position Sensor.
EGR switch valve.
Fuel Injectors

Things I have done are:
#1) Thinking the IAC may be bad, I started the engine and it was idling right around 650rpm......shut engine off, disconnected the Idle Air Control electrical connector......started the engine with IAC disconnected and the engine rpm settled at 1,500.....so I'm thinking the IAC is good.

#2) Thinking the EGR valve may be stuck, I disconnected it'* vacuum hose and applied vacuum to the diaphram. The motion of the valve was smooth and it held vacuum. So as far as the EGR itself goes, I guess it'* fine.

#3) I disconnected the vacuum switch for the EGR valve and the engine runs really good......when I reconnect the switch, engine vacuum opens the EGR as it normally would and the engine misfires.

#4) Took the Blazer over to my buddy'* smog shop. He measured the emissions and said the engine is running rich.

#5) Swapped the MAP sensor with one that I know to be good......still no change.

Any ideas?

Have it scanned for diagnostic trouble codes to see if it is random misfire or on particular cylinders. Check the vacuum hose off the fuel pressure regulator to see if you smell fuel. If you do, replace the FPR.