Dealership said time to replace engine - or take a gamble on intake manifold gasket?

My 99 Mustang has 192,000 miles, runs great. Several years ago almost overheated it, hose blew, bandaged hose up, tried to limp home, keeping an eye on heat gauge. Would pull over and add a bit of water sometimes - 15 minute drive - hose had blown again right next to the bandaged part, turns out electric cooling fan had failed. Was told it could have overheated due to loss of coolant without gauge ever entering red zone due to lack of coolant.

Car still runs great, just drove an hour and half again - but oil leaked into coolant awhile back. Dealership flushed cooling system, eventually replaced the oil soaked radiator hoses. Was fine for quite a while, now dealership said oil was in coolant again. Made appointment for them to do the flush, they stated they don't want to work on it, that it needs a new engine. Told my another mechanic good bet is the intake manifold gasket, dealership feels not worth the money to try it. Engine has been pressure tested several times, had the radiator cap replaced, radiator is not that old -

Should I get another shop to look at the intake manifold possibility? 2nd shop says weird that it is running great for it to be something serious - I am in the San Diego county area - Lakeside, CA - This is the 3.8 6 engine, and auto -

No, not planning on doing work myself - I feel more comfortable putting money into my car over time than trying to afford an expensive car payment - if I bought a new car, I would need to get a hybrid to offset some of the cost - would rather keep my beloved Mustang - the car is running excellent - talked with the Dyno shop here - they asked if the intake manifold gaskets could do this - leak oil into coolant - which is not very common - would this occur if the intake manifold gaskets failed? Car does have sentimental value, and has been well maintained - it runs great -