If your 1991 Ford Thunderbird can't go over 40 mph, it could be due to several potential issues. Common problems include a malfunctioning transmission, a clogged fuel filter, or issues with the ignition system, such as worn spark plugs or ignition coils. Additionally, a failing mass airflow sensor or exhaust restrictions could limit performance. It's best to have a mechanic diagnose the issue for a precise solution.
I realize this is written for a Ford Taurus; however, the steps should be exactly the same:http://www.taurusclub.com/forum/index.php?showtopic=52556
Check over at www.tccoa.com and they can help you out with anything you need.
could be you have water in your distributer
Ford has released many different model cars over the years it has been in business. Some of the models released in 1955 were the Ford Thunderbird, Mystere and Crown Victoria.
R12, which is very expensive. Have it changed over to a newer refrigrant.
For a 1995 Ford Thunderbird : YES , the 4.6 liter Single Over Head Cam ( SOHC ) V8 engine was an option
If its an LX or V8 I'm told around 110-120mph. If its a SC with the supercharged 3.8 V6 over 140mph
It snaps in and laps over lower part of window one bolt by door handle
My 95 Ford Thunderbird service manual shows the scan tool plug-in (Data Link Connector) on the R.H. side of the instrument panel, under the glove compartment door and on the R.H. side of the engine compartment over the wheel well. This is for the 3.8L V6 engine.
Bad Starter....
water in the oil, oil in the water, smoking while running, over filled oil with a weird color
i would check to see if it has spark and i would check your fuses under the hood