American Motors: Vapor Lock, I think, vapor lock, test gas

Question
Hello,
I wanted to write to you tonight to find out what is going on with my brothers car. About two weeks ago, I took his Buick to NY, on the way up there, we ran into a problem. I will explain to you what it felt like, when things went wrong. We were just riding along, running about 70 miles an hour and all of a sudden the car started bucking and cutting in and out. It felt as if were vapor locking on me or what I would think a vapor lock would feel like. It was about 90 degrees outside at the time. We pulled off on an exit and I could feel the car acting like it wanted to just take off and go but then it would cut back, again like a vapor lock. I called my brother and he said that it had done that to him a few time's, just let it set for about 15 min and it would be ok. So we did this and sure enough it was ok, for a little while. About 50 miles later, it started in again. We did the same thing and it worked again but this time only for about 10 miles. Then again and this time for like 50 miles. We did not have this problem again the next day, going 250 miles into NY but we did start off earlier in the day and it was some cooler. We used some feul cleaner in it and we changed out the Air filter and the feul filter too, after this problem. Right before we went to leave NY, we had stopped and left the air and engine running for about 30 min. when we went to drive off, the problem was back again. On the trip back, this did not happen for about 200 miles and then it started in again and again the next day, after about 300 miles. I don't know if this is a problem because of the Air Conditioning or the heat or what. Do you happen to have any idea of what might have caused this problem?
When I was in NY, I was riding with my cousin and she was driving their Pontiac Bonivile (sorry if I have misspelled this). She had the same problem with her car. We got off the road and got her some high test gas and also come fuel cleaner and that seemed to do the trick or because we had stopped and let it cool off, not sure why but things were better right then but they are still having problems with it, from time to time.
My other Cousin have a Chev. Blazer, same problem with them. My cousin said that maybe it was because of the overdrive in each of the auto's. I told him, even though we all have overdrive, none of us use it, so if it is a problem, it was not due to us using it. He said something about a co2 thing or something, not sure about that.
Any help you can give me will be greatly appreciated.
Have A Great Day,
Tim :)

Answer
It could be a fuel pump that is not producing the right pressure or not the right pressure continuosley If the car has electronic ignition, It can be caused by adefective or intermittent control box. Which will not allow the spark to happen correctly.



The problem could also be if the exhaust gas recirculation system (EGR Valve) Does the transmission selector have the overdrive symbol on the quadrant. (You would look for it because it would tell you if it is a overdrive transmission or a Torque converter lock-up system.) An overdrive system actually changes the gear ratio. A lock-up Torque Converter eliminates power loss due to natural slippage of the fluid on the Toque Converter. When was the last time the spark plugs were changed. That could be the ignition problem