[Xeen]

You have provided very little information on what you have and haven't done to the engine so here's what I recommend.
You need to check the compression on all cylinders first and foremost.
There is a really good chance that the camshaft and entire valve train is pretty worn at 150k miles, you are probably floating valves left and right.
Have you rebuilt the carburetor since you have owned it.
I would pull out the gas tank and have it hot tanked, don't put the old fuel back in it afterwords.
I would also rebuild or change out the distributor, replace the timing chain and gears and then put a timing light on it and calibrate it properly.
I would also change out the plugs and install NGK G-power platinums.
You also need to completely go through the vacuum system and replace everything.
You also need to buy some spark plug wire seperaters and heat shields and organize them to keep them away from your exhaust manifold.
You need to basically completely go through the entire engine and troubleshoot it and recondition it and bring it back from the dead, it is very old and needs some serious attention.