just a short word to me and my Firebird. It's a '68 350 convertible with manual 4-speed transmission and deluxe interior. I bought it in 1993 in California during a longer stay in the US and then brought it to Germany, where I live.
The car did well for many years, but about 10 years ago, I got the engine rebuilt by a "specialist" for US cars. After that I didn't run well anymore. There was almost no idle, no power and it almost did not start, when it was hot. You could only start it by a jump cable or by pushing it.
They tried to fix it and made it even worse. The shop went out of the business (which was good), but my problem was not solved. So I stored it in a garage for 2 years, before getting it checked by another mechanic. He found out, that the other mechanic had put Chevy valves into the heads. Obviously they did not listen to me, when I told them, that it is a Pontiac and not a Chevy engine. The rebuilding of the heads solved most problems, but not all. I still had the idle and starting problem.
So the idea came up, that there might be more Chevy parts hidden somewhere. Taking it all apart again or buying a new engine was the question. I decided to get a new one (400).
The engine was built in and I could drive the car after almost 10 years of problems. I thought!
But: The problem is still there … with the new engine! As Long as the engine is cold or cool, it works and starts well. As soon as the engine gets warm the idle goes down, so I have to keep it up by foot. And when it stopps, I cannot start it with the starter. Nice on traffic lights!
My mechanic checked the starter, which is a new. He checked the carburetor, which is new as well. An he finally run out of ideas. Same to me. I think, it must be something electrical, because the engine starts by jump starting. The battery is okay an all the cables look good.