Larry B

I have a 1992 Ford E-250 van with the 4.9L engine. I bought it about a year ago, and it ran pretty well for a while although the check engine light was on. A code reader indicated a problem with the EGR system. Then a few months back it began to start harder and harder and run very rough until the engine warmed up. The problem got worse every week, so I decided to replace a few things. I replaced the distributor cap, rotor, and coil (the plugs and wires were replaced soon after I bought the van), but the problem remained. I decided to replace the EGR valve, but when I started the van after putting the new valve there was a moderately loud bang, followed by a throaty roar from the engine near the manifold (I believe I have blown an exhaust manifold gasket, which looks like no fun to replace but I can do it). I let the engine run a bit, and it was idling very rough, basically like it had before, but after a few minutes the heat shielding that surrounds the pipe that goes from the EGR valve to the exhaust began to smoke, it was burning. I shut her down, then tried it again a little later, with the same results. Just in case I might have had the wrong EGR valve, I put the old one back in. Same thing- heat shield starts to smoke. So two questions: 1) given my admittedly brief description, does anybody agree with the diagnosis of a blown gasket; and 2) what would cause the pipe from the EGR valve to the exhaust to get hot enough to burn the heat shielding, and how do I fix it?